Allow Builda to be ran as a CLI tool (no UI)

[czechboy0]

Seems to be tricky. I'm trying to have a separate target which doesn't have to be linked with AppKit (because it doesn't have any UI), but CLI tools can't have embedded frameworks (and Builda is spread across multiple ones).

I found this article, but it doesn't allow for Swift code in the CLI target itself: http://colemancda.github.io/programming/2015/02/12/embedded-swift-frameworks-osx-command-line-tools/ So I could do this, but it's very hacky and ugly IMO. If anyone finds a better solution, I'm all yours.

[czechboy0]

With the recent addition of multi-repo support, I don't see any benefits of creating a standalone CLI utility. The only thing I can look into is auto-launching Buildasaur on login (and Buildasaur itself already has a autostart syncers option, so that it starts syncing whenever you launch it). See #177.