Implements config property for disabling the prezi button

app.js

 var sessionTerminated = false;
 
 function init() {
+    Toolbar.setupButtonsFromConfig();
     RTC = setupRTC();
     if (RTC === null) {
         window.location.href = 'webrtcrequired.html';

index.html

                         </a>
                         <span id="unreadMessages"></span>
                     </span>
-                    <div class="header_button_separator"></div>
-                    <a class="button" data-toggle="popover" data-placement="bottom" content="Share Prezi" onclick='Prezi.openPreziDialog();'>
-                        <i class="icon-prezi"></i>
-                    </a>
+                    <span id="prezi_button">
+                        <div class="header_button_separator"></div>
+                        <a class="button" data-toggle="popover" data-placement="bottom" content="Share Prezi" onclick='Prezi.openPreziDialog();'>
+                            <i class="icon-prezi"></i>
+                        </a>
+                    </span>
                     <span id="etherpadButton">
                         <div class="header_button_separator"></div>
                         <a class="button" data-toggle="popover" data-placement="bottom" content="Shared document" onclick='Etherpad.toggleEtherpad(0);'>

toolbar.js

 var Toolbar = (function (my) {
 
+    /**
+     * Disables and enables some of the buttons.
+     */
+    my.setupButtonsFromConfig = function () {
+        if(config.disablePrezi)
+        {
+            $("#prezi_button").css({display: "none"});
+        }
+    }
+
     /**
      * Opens the lock room dialog.
      */