Updates CONTRIBUTING guide

Author: sagikazarmark

CONTRIBUTING.md

@@ -3,64 +3,58 @@
 If you're here, you would like to contribute to this repository and you're really welcome!
 
 
-## Coding standard
+## Bug reports
 
-This repository follows the [PSR-2 standard](http://www.php-fig.org/psr/psr-2/) and so, if you want to contribute,
-you must follow these rules.
+If you find a bug or a documentation issue, please report it or even better: fix it :). If you report it,
+please be as precise as possible. Here is a little list of required information:
 
+ - Precise description of the bug
+ - Details of your environment (for example: OS, PHP version, installed extensions)
+ - Backtrace which might help identifing the bug
 
-## Feature request
 
-If you think a feature is missing, please report it or even better implement it :). If you report it, describe the more
-precisely what you would like to see implemented and we will discuss what is the best approach for it. If you can do
-some search before submitting it and link the resources to your description, you're awesome! It will allow us to more
-easily understood/implement it.
+## Security issues
 
+If you discover any security related issues, please contact us at [security@php-http.org](mailto:security@php-http.org) instead of submitting an issue on Github.
 
-## Bug report
 
-If you think you have detected a bug or a doc issue, please report it or even better fix it :). If you report it,
-please be the more precise possible. Here a little list of required informations:
+## Feature requests
 
- - Precise description of the bug
- - Details of your environment
+If you think a feature is missing, please report it or even better: implement it :). If you report it, describe the more
+precisely what you would like to see implemented and we will discuss what is the best approach for it. If you can do
+some search before submitting it and link the resources to your description, you're awesome! It will allow us to more
+easily understood/implement it.
 
 
-## Bug fix
+## Sending a Pull Request
 
-If you're here, you are going to fix a bug and you're the best! To do it, first fork the repository, clone it and
-create a new branch with the following commands:
+If you're here, you are going to fix a bug or implement a feature and you're the best! To do it, first fork the repository, clone it and create a new branch with the following commands:
 
 ``` bash
 $ git clone git@github.com:your-name/repo-name.git
-$ git checkout -b bug-fix-description
+$ git checkout -b feature-or-bug-fix-description
 ```
 
-Then, install the dependencies through [Composer](https://getcomposer.org/):
+Then install the dependencies through [Composer](https://getcomposer.org/):
 
 ``` bash
 $ composer install
 ```
 
-When you're on the new branch with the dependencies, code as much as you want and when the fix is ready, don't commit
-it immediately. Before, you will need to add tests and update the documentation. For the tests, everything is tested with
-[PHPUnit](http://phpunit.de/), the documentation is in markdown format in the `gh-pages` branch.
+Write code and tests. When you are ready, find the testing command in the [README](README.md) and execute it. (This is usually [PHPUnit](http://phpunit.de/) or [PHPSpec](http://phpspec.net/))
 
-To run the tests, use the following command:
+When you are ready with the code, tested it and documented it, you can commit and push it with the following commands:
 
 ``` bash
-$ vendor/bin/phpunit
+$ git commit -m "Feature or bug fix description"
+$ git push origin feature-or-bug-fix-description
 ```
 
-When you have fixed the bug, tested it and documented it, you can commit and push it with the following commands:
+**Note:** Please write your commit messages in the imperative and follow the [guidelines](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html) for clear and concise messages.
 
-``` bash
-$ git commit -m "Bug fix description"
-$ git push origin bug-fix-description
-```
+Then [create a pull request](https://help.github.com/articles/creating-a-pull-request/) on GitHub.
 
-If you have reworked you patch, please squash all your commits in a single one with the following commands (here, we
-will assume you would like to squash 3 commits in a single one):
+Please make sure that each individual commit in your pull request is meaningful. If you had to make multiple intermediate commits while developing, please squash them before submitting with the following commands (here, we assume you would like to squash 3 commits in a single one):
 
 ``` bash
 $ git rebase -i HEAD~3
@@ -71,5 +65,16 @@ If your branch conflicts with the master branch, you will need to rebase and rep
 ``` bash
 $ git remote add upstream git@github.com:php-http/repo-name.git
 $ git pull --rebase upstream master
-$ git push origin bug-fix-description -f
+$ git push -f origin feature-or-bug-fix-description
 ```
+
+
+## Coding standard
+
+This repository follows the [PSR-2 standard](http://www.php-fig.org/psr/psr-2/) and so, if you want to contribute,
+you must follow these rules.
+
+
+## Semver
+
+We are trying to follow [semver](http://semver.org/). When you are making BC breaking changes, please let us know why you think it is important. In this case, your patch can only be included in the next major version.