Add release notes for Review Board 2.5.5.

Review Request #8169 — Created May 17, 2016 and submitted — Latest diff uploaded

Information

Review Board
release-2.5.x

Reviewers

This covers the new support for Mercurial and Subversion on
CodebaseHQ.com, e-mails for API tokens, the re-introduction of the
review group user selector, hosting service auth forms, PostgreSQL
condensediffs fix, and other bug fixes.

Built and read through the docs.