editorial comments - pass '__return_false' as end-callback arg

see https://github.com/Automattic/Edit-Flow/pull/228#issuecomment-30974967
Merge pull request #229 from jkovis/master

when displaying editorial comments in post_meta box pass '__return_false' as end-callback arg
Fix up readme, add readme.txt to better support WordPress.org requirements for readme's in plugins.
Merge branch 'master' of github.com:Automattic/Edit-Flow
Final readme and versioning changes for v0.8
Fix readme.