merge packages with the same name from different repos

[vgmoose]

This is a necessary feature to truly allow multiple repos to freely be added without worrying about package names overlapping.

Ideally, this would go as far as checking the version number and always treating the repo with the newest update as the canonical resource.

However, due to the way version numbers are currently handled (as only strings), it may have to use to the repo priority order that is loaded in the repos.json

[vgmoose]

As of e4853e3, name collisions are no longer a problem. The later repos in repos.json will take priority over the earlier ones.

The other stuff can be done in #21 to allow for actual intelligent versioning that can tell when a name-collision package is newer or older than another one.