FilePatchController integration tests stages and unstages individual lines when the stage button is clicked on a hunk with selected lines

[smashwilson]

Seen on AppVeyor:

Error: Timeout of 60000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves.
    at C:\projects\github\node_modules\mocha\lib\runnable.js:232:19