(CPR-54) Move ship_repo_configs into Pkg::{Rpm,Deb}::Repo

Rather than invoke rake tasks from the newly librarified deb repos
methods, it is far cleaner to invoke other ruby methods. This commit
breaks up the ship_repo_configs task into a Deb and Rpm version and adds
it to the Deb and Rpm repos modules. The ship.rake task is also updated
to invoke both methods.