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`
What do you think about echoing the whole output in red when the command returned an error?