Check version mismatch between top level cabal file and git submodules

[erikd-ambiata]

Currently if the current version specified in the cabal file of a git submodule can't satisify the the version requirements specified in the top level cabal file, then mafia will call cabal with version requirements that cannot be satisfied resulting in a huge difficult to understand error message.

This should be easy to check for and then if a problem exists, produce a simple, easy to read and understand error message.