There are additional depedencies on top of the binary base that are
needed to build and install source components.
This commit moves the base image for source installs from a symlink to
it's own layer, and adds the dependencies that will be needed to install
keystone (more can be added as we add new components).
Partially-Implements: blueprint install-from-source
Change-Id: I56ef6eafb95530e975988dffb62606309dba274e
370736abb7