SERVER-15118 While _rsConfig is synchronization type MX, _rsConfigState is type M.

Consulting _rsConfigState requires holding the mutex, even in executor context,
because _rsConfigState may be changed outside of executor context.
SERVER-14843: Fix mongosniff for decoding messages without a namespace
SERVER-5022 cleanup keypattern.h and shardkey.h, remove dead code
Merge remote-tracking branch 'upstream/master'