Correct icons for select, check and radio + Add support for bootstrap checkbox and radio buttons + add support for specific help-block container

[elkami12]

First thanks for your work !

This pull request is for:

• adding support for bootstrap checkbox and radio buttons group. For example, this can be added easily in your angular app using angular-strap module
• remove insertion of validationState icons for radio, checkbox and select element. This avoid wired display for this kind of input since according to bootstrap documentation:

Feedback icons only work with textual elements.

• add a new feature for inserting help-block in specific place. Sometime it can be useful to be able to set precisely where the help-block should be added if element becomes invalid.
  Now you can just put a container with help-block-cont class inside the form-group to force the help-block to be added in it.
  It is particularly useful with horizontal forms with grid structure.
  Example:

<div class="form-group">
    <label for="xxx" class="col-sm-5 control-label">Label_XXX</label>
    <div class="col-xs-6 col-sm-2">
        <input id="xxx" name="xxx" ng-model="vm.xxx" type="number" class="form-control" required>
    </div>
    <div class="col-xs-6 col-sm-5">
        <p class="form-control-static">more text</p>
    </div>
    <div class="clearfix"></div>
    <div class="col-xs-12 col-sm-7 col-sm-offset-5 help-block-cont"></div>
</div>

Cordially and sorry for my english...