We wait until rings are ready, but the capability server is notified
asynchronously through riak_core_ring_events:ring_update and we were
sometimes querying the capability too soon. Now uses wait/retry logic.
Also, removing sleep timers from cap server restart. Now using
wait/retry also to detect a new cap server process.
Merging involved changing `deploy_nodes` and `build_cluster` to
support both mixed-version deployment as well as supplying
initial app.config overrides.
Updated all tests from both side of the merge to support new API
Conflicts:
src/rt.erl
src/rtdev.erl
