Added twig filter to edit the source url

Added a twig filter to turn urls like `git@bitbucket.org:Comapny/repo.git` into `http://bitbucket.org/Comapny/repo.git`

Without this fix, the link to any release would be `http://satis-domain.com/git@bitbucket.org:Comapny/repo.git`. 
this way of turning SSH urls into source urls is OK for bitbucket (or github), but not in the general case. You cannot assume all servers will have an HTML viewer for their git repo following this pattern