Automate Pairing of Tools/Main

[shatterednirvana]

We would like some mechanism that can ensure that a given revision of the tools will work with the main branch.

[shatterednirvana]

So the problem stems from the fact that a certain set of tools (whether they be bound to a particular branch or user) are designed to work with a given branch/user's main code base, and tend not to work in a mix-and-match fashion.

Therefore, we'd like a mechanism that can tell users "this set of tools will not work with the AppScale image you are trying to run" when they try to run appscale-run-instances. Need to think about how this works on Xen/KVM, Euca. and EC2 and how to make it consistent across all of them.