Additional Source Control providers support

[Andargor]

@Bajee;11486

There is a blueprint diff tool. This wouldn’t work on the command line or from external tools.

@enlight_2014;11494

There is however a built-in visual Blueprint diff tool in the Editor, but to use that tool the Editor has to be able to read the change history from the repository you have your assets stored in.

I did not know this. Granted, that is useful.