Stick in callback so Nt works

 - This fix enables `2t` to open two new tabs, even in incognito.
Include callback in the call chain so that numbered commands can work.

background_scripts/main.coffee

@@ -163,9 +163,10 @@ openUrlInCurrentTab = (request) ->
 #
 # Opens request.url in new tab and switches to it if request.selected is true.
 #
-openUrlInNewTab = (request) ->
+openUrlInNewTab = (request, callback) ->
   chrome.tabs.getSelected(null, (tab) ->
-    chrome.tabs.create({ url: Utils.convertToUrl(request.url), index: tab.index + 1, selected: true, windowId: tab.windowId }))
+    chrome.tabs.create({ url: Utils.convertToUrl(request.url), index: tab.index + 1, selected: true, windowId: tab.windowId },
+                         (tab) -> callback()))
 
 openUrlInIncognito = (request) ->
   chrome.windows.create({ url: Utils.convertToUrl(request.url), incognito: true})
@@ -231,7 +232,7 @@ moveTab = (callback, direction) ->
 # These are commands which are bound to keystroke which must be handled by the background page. They are
 # mapped in commands.coffee.
 BackgroundCommands =
-  createTab: (callback) -> openUrlInNewTab({ url: Settings.get("newTabUrl") })
+  createTab: (callback) -> openUrlInNewTab({ url: Settings.get("newTabUrl") }, (tab) -> callback())
   duplicateTab: (callback) ->
     chrome.tabs.getSelected(null, (tab) ->
       chrome.tabs.duplicate(tab.id)