Allow git init in Elegit

[erictwalker18]

There's a jgit command for it, so why not support it?

http://download.eclipse.org/jgit/site/4.6.0.201612231935-r/apidocs/org/eclipse/jgit/api/InitCommand.html

[dmusican]

Gotta think through what this means for the Elegit interface without having a remote.