Fixes silent deletion of environments

Now environment deletion is done as a regular deployment that can fail.
Environments that are deleted, but deletion process has failed remain in database
and shown in dashboard with status 'delete failure'. Environments that are being deleted
has status 'deleting' and do not disappear before they really got deleted on engine side

Also improved status reporting for environments. Now it also reports status of last deployment -
'deploy failure', 'delete failure'

P.S. Functional tests were slightly refactored and fixed to reflect changes
in deletion logic

Change-Id: I05625dd71f7ca9559bb88319b26b122214f15019
Closes-Bug: #1325101
Merge "Fixes silent deletion of environments"