Release Notes: 0.4.0rc2

What's new since 0.4.0rc?

/!\ Warning /!\ If you have been using a version of the release branch between 0.4.0rc and 0.4.0rc2 (more precisely, in the range 0335aa1432bdb0a8b5bdbefa98f7c2cd95fc72d2^..0.4.0rc2^), and used git cinnabar download and run on Mac or Windows, please run git cinnabar download again with this version and then ensure your mercurial clones have not been corrupted by case-sensitivity issues by running git cinnabar fsck --manifests. If they contain sha1 mismatches, please reclone.
Updated git to 2.11.0 for cinnabar-helper
Improvements to the git cinnabar download command
Various small code cleanups
Improvement to the experimental support for pushing merges.