MB-8903: First version of couch_upr

See test/02-couch-upr.t for the API usage.

This commit also adds the fake UPR server.

Change-Id: I670f8e36196057399b4f942c7ffebfbdb9295066
Reviewed-on: http://review.couchbase.org/29402
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>
Tested-by: Volker Mische <volker.mische@gmail.com>