PYCBC-97: Support host list

Change-Id: I205078590029687f10ce05531072c288ac61c944
Reviewed-on: http://review.couchbase.org/25996
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Mordechai Nunberg <mnunberg@haskalah.org>