Don't depend on context.revisions anymore
Don't depend on context.revisions anymore

We don't want to run the fetchRevisions hook in every command
that might need it (i.e. `deploy` and `activate`). Plugin authors
should implement a private function that fetches revisions if a
plugin needs that to function correctly.

See https://github.com/ember-cli/ember-cli-deploy/pull/209 for
a discussion about this.

vitch/ember-cli-deploy-s3-index,elidupuis/ember-cli-deploy-s3-index,elidupuis/ember-cli-deploy-s3-index,ember-cli-deploy/ember-cli-deploy-s3-index,LevelbossMike/ember-cli-deploy-s3-index,LevelbossMike/ember-cli-deploy-s3-index,ember-cli-deploy/ember-cli-deploy-s3-index,elidupuis/ember-cli-deploy-s3-index,LevelbossMike/ember-cli-deploy-s3-index,vitch/ember-cli-deploy-s3-index