Fixes #7465: display message when there aren't any subscriptions.

http://projects.theforeman.org/issues/7465
fixes #7422 - documenting the `label` param for env creation, BZ 883170
Merge pull request #4665 from komidore64/rmi7422-label-on-env-create

fixes #7422 - documenting the `label` param for env creation, BZ 883170
Merge pull request #4667 from waldenraines/7465

Fixes #7465: display message when there aren't any subscriptions.