Added all sponsors to Bokeh/Pandas event for testing purposes.

Fixed on hover effects for sponsors logos in post and footer (removed JS code, added css).
Created touch_surgery.md and python_software_foundation sponsor file.
Redone Zopa's logo (was low quality).
Removed unused code from site.js.

Author: Tomasz-Kluczkowski

_posts/2017-10-04-Bokeh-As-A-Backend-For-Pandas.md

@@ -10,6 +10,9 @@ image: static/images/events/pandas_bokeh_backend_harvey_nash_960x539px.jpeg
 sponsors: 
     - harvey_nash
     - bloomberg
+    - python_software_foundation
+    - zopa
+    - touch_surgery
 ---
 
 According to this recent blog post by [Stack Overflow](https://stackoverflow.com/), Python is declared as the fastest-growing major programming language.

_sass/post.scss

@@ -73,6 +73,9 @@
     background: rgba(7, 41, 72, 0.53);
     border: #A55605 2px ridge;
   }
+  &:hover > .post__icon {
+    color: antiquewhite;
+  }
 }
 
 .post__icon {

_sass/style.scss

@@ -26,11 +26,6 @@ a {
   margin-right: 0;
 }
 
-.center-block {
-  display: table;
-  margin: auto;
-}
-
 .container-fluid {
     padding-left: 0;
     padding-right: 0;
@@ -500,27 +495,27 @@ a {
 }
 
 .footer__sponsor-link {
-    background: #041729;
-    border-radius: 5px;
-    border: #7fa0c2 1px solid;
-    text-align: center;
-    display: inline-block;
-    line-height: 102px;
-    vertical-align: middle;
-    margin: 1%;
-    width: 278px;
-    height: 102px;
+  background: #041729;
+  border-radius: 5px;
+  border: #7fa0c2 1px solid;
+  text-align: center;
+  display: inline-block;
+  line-height: 102px;
+  vertical-align: middle;
+  margin: 1%;
+  width: 278px;
+  height: 102px;
+  &:hover > .footer__img  {
+    filter: none;
+    -webkit-filter: grayscale(0);
+    -webkit-transform: scale(1.05);
+  }
 }
 
 .footer__img {
   filter: gray;
   -webkit-filter: grayscale(1);
   transition: filter, .8s ease-in-out;
-  &:hover {
-    filter: none;
-    -webkit-filter: grayscale(0);
-    -webkit-transform: scale(1.05);
-  }
 }
 
 .footer__link {

_sponsors/python_software_foundation.md

@@ -0,0 +1,7 @@
+---
+sponsor_id: python_software_foundation
+sponsor_name: "Python Software Foundation"
+sponsor_logo: static/images/sponsors/python_software_foundation.png
+sponsor_link: https://www.python.org/psf/
+---
+The Python Software Foundation (PSF) is a non-profit corporation that holds the intellectual property rights behind the Python programming language. We manage the open source licensing for Python version 2.1 and later and own and protect the trademarks associated with Python.

_sponsors/touch_surgery.md

@@ -0,0 +1,7 @@
+---
+sponsor_id: touch_surgery
+sponsor_name: "Touch Surgery"
+sponsor_logo: static/images/sponsors/touch_surgery.png
+sponsor_link: https://www.touchsurgery.com/jobs.html
+---
+ The Touch Surgery platform is an interactive surgical simulator for healthcare professionals; providing a realistic and detailed guide to every step of a procedure. Users can quickly learn surgery, instantly test their knowledge, and rehearse for surgery.

static/images/sponsors/zopa.png

@@ -7,18 +7,8 @@ var navigationButtonClose = $(".navigation__button-close");
 $(document).ready(function () {
     buttonOpenContainer.on("click", openNav);
     navigationButtonClose.on("click", closeNav);
-    buttonHover();
-    
 });
 
-function buttonHover () {
-    $(".post__button").hover(function () {
-        $(".post__icon").css("color", "antiquewhite")
-    }, function () {
-        $(".post__icon").css("color", "#7FA0C2")
-    });
-}
-
 function openNav() {
     buttonOpenContainer.css("pointer-events", "none");
     buttonOpenContainer.toggle(500, showCloseButton);