Added support for Node 0.11.13.

Updated to nan 1.20.
Corrected slight incompatabilities with libuv.

Change-Id: Iae131a203885554a2184717253e1ec368d36a93a
Reviewed-on: http://review.couchbase.org/38418
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>
Tested-by: Brett Lawson <brett19@gmail.com>