Separate OSTF and Postgres from nailgun

Enables capability to install nailgun and
OSTF without postgres server for Docker
installation. OSTF moved out of base
Nailgun class so it can be installed
separately. Database paramters are
explicitly declared for OSTF both in
the class and in service definitions.

blueprint fuel-containerization-of-services

Change-Id: I841c328ab932c54ad44e33018511be9c1d5220b3
remove OS release certificates

Change-Id: I6a7830d3f751b9dde1dccefb55c8ec9c4f75bf10
Closes-Bug: #1305090
Merge "remove OS release certificates"
Merge "Separate OSTF and Postgres from nailgun"