Make commandline 'rock' invocation with FAIL notices return 1 to the shell.

[emauton]

The git-hook command already does this:
https://github.com/inaka/elvis/blob/master/src/elvis.erl#L96

I want to use 'elvis rock' with my (separate, post-commit) continuous integration system. I can work around it, but having it fail (from the shell's point of view) would help, and seems the Right Way.

Looking at the code, the proper way to do it is uncertain. Are you comfortable with halting on failure & not processing any more commands in process_options([rock | ...], ...)?
https://github.com/inaka/elvis/blob/master/src/elvis.erl#L194

[elbrujohalcon]

Yeah, @emauton I think that halting there is correct. Would you like to submit a PR with the change?

[emauton]

OK, thanks. I'll do a PR for it.

[emauton]

This is working perfectly in my CI build now. Thanks very much!

[jfacorro]

@emauton Awesome. Thank you for the PR!