Prevent XSS injection using 'nick' on presence

Also allows special characters in displayName. Fixes issue #182.

app.js

 $(document).bind('left.muc', function (event, jid) {
     console.log('left.muc', jid);
     var displayName = $('#participant_' + Strophe.getResourceFromJid(jid) +
-        '>.displayname').text();
+        '>.displayname').html();
     messageHandler.notify(displayName || 'Somebody',
         'disconnected',
         'disconnected');

contact_list.js

         var contactName = $('#contactlist #' + resourceJid + '>p');
 
         if (contactName && displayName && displayName.length > 0)
-            contactName.text(displayName);
+            contactName.html(displayName);
     });
 
     my.setClickable = function(resourceJid, isClickable) {

muc.js

         member.role = tmp.attr('role');
 
         var nicktag = $(pres).find('>nick[xmlns="http://jabber.org/protocol/nick"]');
-        member.displayName = (nicktag.length > 0 ? nicktag.text() : null);
+        member.displayName = (nicktag.length > 0 ? nicktag.html() : null);
 
         if (from == this.myroomjid) {
             if (member.affiliation == 'owner') this.isOwner = true;

videolayout.js

             if (nameSpanElement.id === 'localDisplayName' &&
                 $('#localDisplayName').text() !== displayName) {
                 if (displayName && displayName.length > 0)
-                    $('#localDisplayName').text(displayName + ' (me)');
+                    $('#localDisplayName').html(displayName + ' (me)');
                 else
                     $('#localDisplayName').text(defaultLocalDisplayName);
             } else {
                 if (displayName && displayName.length > 0)
-                    $('#' + videoSpanId + '_name').text(displayName);
+                    $('#' + videoSpanId + '_name').html(displayName);
                 else
                     $('#' + videoSpanId + '_name').text(interfaceConfig.DEFAULT_REMOTE_DISPLAY_NAME);
             }
     }
 
     my.inputDisplayNameHandler = function (name) {
-        if (nickname !== name) {
+        if (name && nickname !== name) {
             nickname = name;
             window.localStorage.displayname = nickname;
             connection.emuc.addDisplayNameToPresence(nickname);
         var displayName = resourceJid;
         var nameSpan = $('#' + videoContainerId + '>span.displayname');
         if (nameSpan.length > 0)
-            displayName = nameSpan.text();
+            displayName = nameSpan.html();
 
         console.log("UI enable dominant speaker",
             displayName,