Add unload confirmation on live preview, edit, and create.

lib/gollum/frontend/public/gollum/livepreview/js/livepreview/livepreview.js

@@ -1,4 +1,6 @@
 (function () {
+window.onbeforeunload = function(){ return "Leaving Live Preview will discard all edits!" };
+
 var converter = Markdown.getSanitizingConverter();
 var editor = ace.edit("editor");
 var editorSession = editor.getSession();

lib/gollum/frontend/templates/create.mustache

@@ -9,6 +9,7 @@
 </div>
 </div>
 <script type="text/javascript">
+window.onbeforeunload = function(){ return "Leaving will not create a new page!" };
 jQuery(document).ready(function() {
   $.GollumEditor({ NewFile: true, MarkupType: '{{default_markup}}' });
 });

lib/gollum/frontend/templates/edit.mustache

@@ -11,6 +11,7 @@
   <div id="wiki-content">{{>editor}}</div>
 </div>
 <script type="text/javascript">
+window.onbeforeunload = function(){ return "Leaving will discard all edits!" };
 jQuery(document).ready(function() {
   $.GollumEditor();
 });