store user, token and role as headers in http request for further use

... by audit code

Change-Id: I2b6ab5e60cda46bd8aeb94a9f2c68752aed7e53c
Reviewed-on: http://review.couchbase.org/43066
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>