MB-100: dont send otpCookie to UI

Change-Id: I2088e824b21213898665d3f4cf5a0fa8a3fe4f0d
Reviewed-on: http://review.couchbase.org/27950
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>