Parametrized paths for components in test config

Parametrized paths for keystone, glance, nova, reddwarf components
and set the appropriately in the test config. This is needed for the
vm-gate integration piece. The vm-gate doesn't use /opt/stack as the
location of the OpenStack components, so these need to be parametrized
and set correctly.

Fixes bug 1103718

Change-Id: I54bcf15af1423e22b2efef722eb19c222fce766e