Add back old projects to replicate to git.o.o

When projects are removed from review.projects.yaml they cease
to be replicated to our git server, but continue to live on
github. We should probably keep them on git.o.o, so updating
review.projects.yaml to include them.

Re-adding:

 - openstack/melange
 - openstack/python-melangeclient

Change-Id: I311298c6b91ed7de34bbc21f8cdb70e1471db4e7
Closes-Bug: #1288485
Merge "Add back old projects to replicate to git.o.o"