Add release notes for Review Board 2.0.7.

Review Request #6298 — Created Sept. 4, 2014 and submitted — Latest diff uploaded

Information

Review Board
release-2.0.x
1af97fe...

Reviewers

This covers all the fixes and improvements made since 2.0.6, including
numerous Local Site fixes, better error messages, and SCM compatibility
improvements.

Built the docs and read through them.

Building the docs didn't produce any errors.