NCBC-172: RestSharp is new default HTTP client for views

Change-Id: I624ea571dfb5cadaac4f889ece9c2c6a3a283dea
Reviewed-on: http://review.couchbase.org/23786
Reviewed-by: Saakshi Manocha <saakshi.manocha@globallogic.com>
Tested-by: Saakshi Manocha <saakshi.manocha@globallogic.com>