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`. 
Yep use this in your pkg
```
{
    "support": {
        "source": "http://github.com/linkto/myrepo"
    }
}
```