Delete Heat stack when environment is deleted

Added new action 'destroy' to io.murano.Environment that handles
deletion of Heat stack when environment is deleted.

Note: changeset include changes in io.murano package, during update
this package should be re-uploaded to application catalog

Closes-Bug: #1321487
Change-Id: I92268b90cb762d58669208aef3f5fce85e06d355
Merge "Delete Heat stack when environment is deleted"