Fix deprecation warning for the context menu

When trying to create tests for my windows supporting PR, i found this :astonished:

![image](https://cloud.githubusercontent.com/assets/238079/5092214/65a007be-6f1b-11e4-99bc-9a0b6ba66851.png)

This removes the deprecation warning:

![image](https://cloud.githubusercontent.com/assets/238079/5092284/e63b004a-6f1b-11e4-96f2-df1c233060cd.png)

i changed the text of the context menu to `Open in GitHub app` because `GitHub.app` isn't a thing in the magical land we call Windows :wink:. Let me know if you want it to be something else.

Sadly, it doesn't fix my poorly written tests, even after i wished really hard :cry: