Let me know if I'm reading this right.

* I have 2 deprecated keys in `liftoffrc`
* After the first one, liftoff quits with a warning
* I fix that key
* I run liftoff again
* liftoff warns me about the second deprecated key
* I'm like "Why didn't you tell me this before!?!"

That might be a separate PR, though. For now, how about removing this extra `exit 1`, since it's duplicated in `project_configuration.rb`?