Add prepare-gerrit-repos role and gerrit-base job

This role sets up the gerrit submodules, and the base job defines
all of the repos which are needed to build gerrit.  A test job
that inherits from it is added to exercise it.

Change-Id: Ibe5bb0866052c394a53f5f534daa6927a6880da2
10 files changed
tree: fb4300315c8316b1eab3943ccf4ae842569f3ead
  1. playbooks/
  2. roles/
  3. zuul.d/
  4. .gitreview
  5. LICENSE
  6. README