NCBC-316: Allow GetJson to support the retrieval of arrays and lists

Adds support to the CouchbaseClientExtensions.GetJson(…) method to 
handle the deserialization of arrays and lists of objects and not 
just individual objects.

Change-Id: I69704b922c559265b736ca54c3eee32a6aef7d5e
Reviewed-on: http://review.couchbase.org/29746
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>