PYCBC-541: Correct cluster query syntax/docs
PYCBC-541: Correct cluster query syntax/docs

Cluster.query was using an experimental method of forwarding
parameters, in attempt to share parameter information between
OptionBlocks and named parameters. It wasn't as effective as I'd
hoped in PyCharm, so this reverts to simpler, easier to read code.

Also added docs for the function.

Change-Id: I569702539c12ffff898a352f82ca2ee2bf558d93
Reviewed-on: http://review.couchbase.org/110616
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Tested-by: Ellis Breen <9d8041ac7ead8d3e1f3217c04c7ed5e3098c2381@couchbase.com>
Reviewed-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>

couchbase/couchbase-python-client,couchbase/couchbase-python-client