Add repository browser for Kiln Harmony

Fog Creek's Kiln now supports Git.  This repository browser
implementation borrows heavily from the GithubWeb and CGit browsers.

I tested the implementation by running "mvn install", then copied target/git.hpi to $JENKINS_HOME/plugins/, restarted the server, and configured the plugin with my repo's URL.  I then verified that the links on a changeset for an edited file were as expected and the same as those that Kiln generates in all 3 cases: full changeset diff, the diff of a single file in a changeset, and single file history.