Convert SoapClient to use the new db module

- Uses the db_session filter and db module magic to get templates
  for SOAP testing, no longer using SSH and psql commandlines
- The above change breaks SOAP tests for 5.2, which is a bug against
  the 5.2 appliance build: https://github.com/ManageIQ/cfme_build/issues/130
- soap_base fixture removed; it looked to be a namespace created to
  make it easy to get at the SSH client, which is no longer used
  in the SOAP tests.
- Refactoring some things over into utils, such as:
  - SoapClient is now utils.soap soap_client
  - SoapClient.ssh_client is now utils.ssh ssh_client
- Double-checked test fixture usage, pared down where possible