docs(README): update dev documentation
Merge pull request #72 from bacongobbler/docs

docs(README): update dev documentation
fix(Makefile): ensure the installer makes /var/lib/deis/units readable
Merge pull request #73 from mboersma/71-fix-units-refresh-perms

fix(Makefile): ensure the installer makes /var/lib/deis/units readable
fix(state): ignore intermittent timeouts when polling for UnitState
Merge pull request #74 from gabrtv/fix-poll-timeout

fix(state): ignore intermittent timeouts when polling for UnitState
docs(CHANGELOG): update for v0.12.0
chore(release): update version to v0.12.0