Allow direct access when using a registered process

The match_object API currently takes both atoms and pids.
This change allows the atom case to skip a synchronous call
to the gen_server state. The old path remains to allow pids
to continue to work through the old call path since it
can't easily infer the lru objects table name.

BugzId: 26105
Merge pull request #4 from cloudant/26105-match-objects-fastpath

Allow direct access when using a registered process