Link Revision Number

Automatically generate the link for revision numbers in artifacts and time billing description.  The supported revision number format are as follows:

• subversion: r[0-9]+
• git commit: r[0-9a-f]{8,40}, this is a RSH1 unique key

We should be able to generate links for different version control systems, which includes:

• SourceForge
• Trac the link template is something like:
  http://your.site.com/trac/changeset/1234abcef for git repository, 
  http://your.site.com/trac/changeset/1234 for subversion repository,
• github the link template is like: http://github.com/username/projectname/commit/1234abcef
• lunchpad
• more ...?