This commit adds the ability to install Ironic without requiring an
OpenStack-Ansible pip wheel repository.
In 'developer mode' the git source is cloned directly and the services
are installed directly from the git clone with its requirements being
installed from pypi. The OpenStack upper-constraints file is also used
to ensure that the install is executed using the appropriately tested
set of pypi packages.
Change-Id: I38f6b0796fa2bb647e51194907274d9ca6cfb585
5e69f88ed9