Pass cbauth env variables to 2i components

Change-Id: I2f4341f18205b2b29d959e1fb53eed45bd5b3af4
Reviewed-on: http://review.couchbase.org/44679
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>