Fix license header (hopefully once and for all).

I left a reference to NorthScale there.

Change-Id: I852d72bbaa2ab746029f8f71236e59dce3633579
Reviewed-on: http://review.couchbase.org/42941
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>