Update RELEASE_NOTES.txt for release.

Reviewed by: daisy
Resolve SNAPSHOT dependencies before release.
[maven-release-plugin] prepare release kiji-express-0.6.0
[maven-release-plugin] prepare for next development iteration
scratch work
EntityIdComponents
src/main compiles
partway through making tests pass
More tests pass
Almost all tests working
scratch work
more debugging work
Tests pass (was hashed vs formatted row keys)