NCBC-689: Disable ServicePointManager.Expect100Continue by setting to false

Change-Id: I80cad1f0325077d4739467e8a3888608c8edbb20
Reviewed-on: http://review.couchbase.org/42229
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>