Better names for CLI commands, and more friendly way of pushing commits

* "cloudy deploy" is now "cloudy poll", and "cloudy commit" is now
  "cloudy deploy"

* "cloudy deploy" now reads its configuration from .cloudy.yml, in which
  deployment groups are defined. Each deployment group is a list of
  deployments poll URIs, and a branch name. The latest commit from the
  given branch name is retrieved locally, and pushed to all the
  deployments in the group.
bumped version
Merge branch 'release/0.3' into develop