v0.2.1

Changelog

d1ddcee Merge branch 'master' of github.com:mantil-io/mantil
2e22772 add mail html texts
9005a9c add welcome html mail
acc3f3a clean up user-created s3 buckets on stage destroy
85cedee enable welcome mail
6f4b385 fix command help
34b8b51 fix hidden in log wrapped error message
b811a89 switch activation mail to HTML
1f2337e update backend deploy state
d6d617d update backend welcome mail
4b13d2b use html/template for rendering html emails