Seperate install of services and start scripts:

This allows openstack services to be git/pip installed
without installing any startup scripts.

This is useful for keystone-db or nova-db elements, for
example, where the service must be installed to perform
database migration, but no service start scripts need
be installed.

Additionally, add a tool to create openstack sql databases.

Use openstack pypi mirror:

Use the openstack pypi mirror for openstack service
installation. It's much faster than pypi.org.

Also, pip install $svc_repo/tools/pip-requires first,
if it exists, which is required to pick up oslo.config.

Change-Id: I72751d4da59f8597d20aea2f27a9dfabe2f63a8f