Add optional "SVN" url item in repository project page
I create subversion frontend for git repository (https://github.com/bozaro/git-as-svn).
This project add read/write access to git repository via subversion protocol (port 3690) as external service without GitLab modification.
This change add optional url SVN item to GitLab project page.
If you have any suggestions or questions regarding the project / documentation / GitLAb integration, I am ready for dialogue.