Gitblit 0.6.0

* added: federation feature to allow gitblit instances (or gitblit
  federation clients) to pull repositories and, optionally, settings and
  accounts from other gitblit instances. This is something like svn-sync
  for gitblit.
* added: google-gson dependency
* added: javamail dependency
* updated: MarkdownPapers 1.1.1
* updated: Wicket 1.4.18
* updated: JGit 1.1.0
* fixed: syndication urls for WAR deployments
* fixed: authentication for zip downloads