Add a meaningful warning to the failure when the ring file
doesn't have a entry for the current node name.
Merge pull request #354 from basho/slf-vnode-ops-opts

Add #riak_core_fold_req_v2 record, part 1 of 2
Merge pull request #244 from evanmcc/pevm_stale_ring

Clarify error message for stale ring failures.
Merge remote-tracking branch 'upstream/master' into develop