Canonical repository URLs

to: @xaviershay @square/kochiku-contributors 

First commit is making `URL_PARSERS` fancy

Second commit introduces the concept of a canonical url for a repository. This is necessary because if a developer build is requested with the `kochiku_build` script and the repository url is passed up in a format different than the one used in the `url` column in the `repositories` table, Kochiku will fail in its attempt to lookup repository (line 115 of `builds_controller.rb`). When Kochiku fails to find the repository record it will try to create one but the create will fail (as it should) because of the uniqueness validation on name.

If we ensure that we are always using the same url format when querying the repositories table then we can avoid this problem. I have changed this one location in builds_controller but I'm sure there are other places in the code base where we need to use `canonical_repository_url` as well.