[ccache] Moving to github

[Joel Rosdahl]

Hi,

Ever since Tridge handed over the project to me, the main ccache Git
repository has been hosted on git.samba.org and bugs handled in
bugzilla.samba.org. I also have kept an unofficial mirror on github.

Since some time now, almost all activity regarding new features and bug
reports have been circling around the github mirror repository, so I think
that it's time to move to github officially. (It will be located under
github.com/ccache, not under my personal github account.)

If anybody thinks this would be a bad idea, please make some noise.
Otherwise I'll do the move in a week or so.

-- Joel