adds tests for CINDER encryption volume-type APIs

This patch adds the JSON tests for CINDER encryption volume-type V1 APIs.
It also adds the JSON clients for following APIs :
1. cinder encryption-type-delete

Change-Id: I20a68684f950fe36653eb4304edb56e244867ca3
Merge "adds tests for CINDER encryption volume-type APIs"
Remove the list_servers_since_test

This test is mostly just a very good way to add new failures. There
are subtleties on the timestamping of servers which means that this
can often return the wrong number of servers. Because of this we
should just delete the test.

If we want something like this we should create a much more sane setup
that includes getting all the servers, determinging some subset that
the filter should return, fetching those, and getting the count.

Change-Id: I5c08ef031043229b76a6800eeaab6d418fc4614f
Merge "Remove the list_servers_since_test"
Merge branch 'master' of https://github.com/openstack/tempest