JSCBC-911: Fixed MutateInSpec.insert options to be optional.
JSCBC-911: Fixed MutateInSpec.insert options to be optional.

Change-Id: Idc555fb7bd4694a275e558f5977d52e2fb4a25ea
Reviewed-on: http://review.couchbase.org/c/couchnode/+/158978
Reviewed-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>
Tested-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>

brett19/couchnode,couchbase/couchnode,brett19/couchnode,couchbase/couchnode,couchbase/couchnode,couchbase/couchnode,brett19/couchnode