Fix path

.key now returns undefined on failure so path can be 0.
If path is undefined then use an empty string.

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

@@ -62,9 +62,10 @@ initAce( commentEditor, commentEditorSession );
 var baseUrl = location.pathname.split('/').slice(0,-2).join('/');
 
 // RegExp from http://stackoverflow.com/questions/901115/get-query-string-values-in-javascript
+// Returns value on success and undefined on failure.
 $.key = function( key ) {
     var value = new RegExp( '[\\?&]' + key + '=([^&#]*)' ).exec( location.href );
-    return  ( !value ) ? 0 : value[ 1 ] || 0;
+    return  ( !value ) ? undefined : value[ 1 ] || undefined;
 }
 
 // True if &create=true
@@ -341,9 +342,9 @@ var applyTimeout = function () {
   /* Load markdown from /data/page into the ace editor.
      ~-1 == false; !~-1 == true;
    */
-  if ( !~location.host.indexOf('github.com') ) {
+  if ( !~ location.host.indexOf( 'github.com' ) ) {
     // ensure leading / is removed from path and that it ends with /
-    var path = unescape($.key( 'path' )).replace(/^\/+/, '');
+    var path = unescape( $.key( 'path' ) || '' ).replace( /^\/+/, '' );
     if ( path.charAt( path.length - 1 ) !== '/' ) {
       path += '/';  
     }