Integrate the Pre-release logic into the interactive script

It seems awkward to need to manually exit the release script when you want to run a pre-release, a la http://wiki.ros.org/bloom/Tutorials/PrereleaseTest#Prepare_the_release 

I feel it would be beneficial to have an option for 
A) Prepare_release for local test
B) Prepare_release for cloud test
C) No pre-release test
