New provider: Gitweb

[bzz]

Gitweb is a Git web interface, written in Perl
(Comparing to CGit is written in C, that we already support)

Some big projects like https://review.tizen.org/git/ use it, so it would be nice to be able to add them to the pipeline by adding a gitweb provide to Rovers.

[smola]

It should be easy to add based on the CGit provider. We need a Bing dork to discover sites. I've been trying git commitdiff -site:github.com which yields quite a lot results.