Helm operator 0.2.1

This is a patch release that allows helm-op to recover from a failed release install. If a chart is broken, Tiller will reserve the name and mark the release as failed. If at a later time the chart is fixed, helm-op can't install it anymore because the release name is in use. Purging the release after each failed install allows helm-op to keep retrying the install.

• Purge release if install fails weaveworks/flux#1344