Fix user@host:path/to/repo.git urls to git://host/path/to/repo.git

per https://github.com/tokuhirom/Minilla/pull/146#issuecomment-60482495,
CPAN::Meta apparently don't like it when we pass through the raw
git repository
Merge pull request #147 from tokuhirom/fix_git_url_format

Fix user@host:path/to/repo.git urls to git://host/path/to/repo.git