Merge pull request #948 from m-voloshin/space-for-ptt

Spacebar is used to activate Push-To-Talk

modules/keyboardshortcut/keyboardshortcut.js

         APP.UI.toggleKeyboardShortcutsPanel();
     }, "keyboardShortcuts.toggleShortcuts");
 
-    KeyboardShortcut.registerShortcut("T", null, function() {
+    // register SPACE shortcut in two steps to insure visibility of help message
+    KeyboardShortcut.registerShortcut(" ", null, function() {
         JitsiMeetJS.analytics.sendEvent("shortcut.talk.clicked");
         APP.conference.muteAudio(true);
-    }, "keyboardShortcuts.pushToTalk");
+    });
+    KeyboardShortcut._addShortcutToHelp("SPACE","keyboardShortcuts.pushToTalk");
 
     /**
      * FIXME: Currently focus keys are directly implemented below in onkeyup.
                 $(":focus").is("input[type=password]") ||
                 $(":focus").is("textarea"))) {
                 var key = self._getKeyboardKey(e).toUpperCase();
-                if(key === "T") {
+                if(key === " ") {
                     if(APP.conference.isLocalAudioMuted())
                         APP.conference.muteAudio(false);
                 }