Move Clone Repository to Dialog

Summary: This moves the clone details on the Repository Home to a button / dialog. Functionally this is to pull content on the page way up, while giving full space to all the clone options. I think we can build this into some FancyJS if needed, but this seems to clean ui the UI dramatically with little overhead. I don't want to attempt the JS dropdown unless we're sure that's the best path (it exposes the most common URI by default, saving a click).

Test Plan: Tested hg, svn, git repositories and the raw URL page. Test close button.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D18203