Remove twitter share button (#121)

It seems to have stopped working.

Author: adamchainz

docs/css/default.css

@@ -36,13 +36,6 @@ body.index-page #main-content iframe.github-star-button {
     margin-right: -15px;
 }
 
-/* Tweet button */
-body.index-page #main-content iframe.twitter-share-button {
-    float: right;
-    margin-top: -12px;
-    margin-right: 8px;
-}
-
 /* Travis CI badge */
 body.index-page #main-content img.travis-build-image {
     float: right;

docs/index.md

@@ -1,8 +1,6 @@
 <p class="badges">
 <iframe src="http://ghbtns.com/github-btn.html?user=tomchristie&amp;repo=django-vanilla-views&amp;type=watch&amp;count=true" class="github-star-button" allowtransparency="true" frameborder="0" scrolling="0" width="110px" height="20px"></iframe>
 
-<a href="https://twitter.com/share" class="twitter-share-button" data-url="django-vanilla-views.org" data-text="Django Vanilla Views... http://django-vanilla-views.org" data-count="none"></a>
-<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="http://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");</script>
 </p>
 
 # Django Vanilla Views