Output rework

Change the output of each command to simply output each git command in bold and the output of that command immediately after. 

Cleanup error messages to follow suit of what `git rebase` errors look like (but print in red to easily catch the eye).

To get a look, run a single cucumber test with the commands printed out.
 `cucumber features/git-ship.feature:3 DEBUG=true`
Okay. Then we should do all the things than run_command does here, like coloring output red in case the command failed.