Handle IRC style mentions

This replaces irc mentions like 'john: ' and 'john, ' to '@john '.
Closes #2

lib/gitter-adapter.js

@@ -148,15 +148,34 @@ Adapter.prototype.sendMessage = function(target, message) {
   var uri = target.replace('#','');
   var isStatus = /^\u0001ACTION/.test(message);
 
+  var regResult = /^((\w+)[:,]\s*).+/.exec(message);
+  var mention = undefined;
+  var mentioned = undefined;
+
   // This are /me IRC messages.
   if (isStatus) {
     message = message
     .replace(/^\u0001ACTION /, '@' + c.nick + ' ')
     .replace(/\u0001$/, '');
   }
 
+  if (regResult !== undefined) {
+    var mention = regResult[1];
+    var mentioned = regResult[2];
+  }
+
   this.gitterClient.rooms.join(uri)
   .then(function(room) {
+    return [room, (room.oneToOne ? [] : room.users())];
+  })
+  .spread(function (room, users) {
+    users.forEach(function (userFound) {
+      if(user.username.toLowerCase() === mentioned.toLowerCase()) {
+        // Mentioned user is in room.
+        message = message.replace(mention, "@" + mentioned + " ");
+      }
+    });
+
     return isStatus ? room.sendStatus(message) : room.send(message);
   })
   .catch(function(err){