Send #doc{} instead of #group{} to remote nodes

I realized after the fact that I'm still doing the evil thing of sending
records between nodes, so in a later two-phase upgrade we should fix
that.  Nevertheless, the RPC workers are now configured to match on the
doc record, and this gets us to CommonJS faster.

BugzID: 13487
Merge pull request #79 from cloudant/13487-send-ddoc-not-group

Send #doc{} instead of #group{} to remote nodes

BugzID: 13487