Make project title link to project homepage

Implements feature request: http://feedback.gitlab.com/forums/176466-general/suggestions/5491715-please-small-fix-click-on-title-of-repo-to-go-to

Make project title link to project homepage. Minor edit that does not appear to negatively affect [any pages used on](https://github.com/gitlabhq/gitlabhq/search?utf8=%E2%9C%93&q=project_title&type=Code).
@bbodenmiller @cirosantilli we have this simple sanitize here because before this commit (020078663e401798d199a1a293ac59d990f81dad) it was possible to xss group/username. Since validation protects us from bad group/namespace names this `simple_sanitize` prevents xss with group names created before `GitLab v5`.  Example of such instance is GitLab.com which is online for long time and had such stuff. Ex: 


![screenshot 2014-10-29 13 50 16](https://cloud.githubusercontent.com/assets/305940/4825144/c5822de8-5f61-11e4-8eaf-37ed9be278c2.png)