Issue4 file commands

Hi, Matt.

Could you please review PR.

I had to create that DocumentMock class since I didn't manage to configure mock for dynamic type using NSubstitute (line 81 in TortoiseGitLauncherServiceTests.cs).
I configured shortcuts for new commands as you suggested Control+Shift+G,*.

Regards,
Stan
Robert, thanks I'll fix it.
Actually I hoped to find a way to get rid of DocumentMock class. But have no ideas how to do it for now.