Revert "Bug 1003788 - [marionette-apps] switchToApp method doesn't wait for the app is rendered on screen"

This reverts commit c06e2ee587fde5e57db32b7b0eb0fffa46fd3a51.
Bug 936520 - [mocha] we can't see console.error in the console
Merge pull request #31 from RickyChien/bug-936520

Bug 936520 - [mocha] we can't see console.error in the console r=@julienw