Nexus2 and Gerrit project builder

Nexus2 and Gerrit project builder

Initial checkin of project build system for Nexus 2 and Gerrit

The script currently does the following:

* takes 2 yaml files (see examples) for configuration
  - settings.yaml == administrative / global settings
  - config.yaml == repository structure to build including nexus
    passwords
* Walks config.yaml for all repositories and creates targets,
  privileges, roles and users based upon our standard configuration

Presently does not create the Gerrit repositories

* Staging repo re-ordering hack script

NOTE: This does not work against Nexus 3 as the REST API has been
removed in Nexus 3. Presently scripting Nexus 3 requires groovy

Change-Id: Ia06444a85e167a1e5685f9e569322c9b0e0b8c97
Signed-off-by: Andrew Grimberg <agrimberg@linuxfoundation.org>