Allow hello before auth in strict mode

HELLO should be allowed at any time even when running
in strict mode

Change-Id: I1e4536a489285f78a26277ccd87e175318c1b7fe
Reviewed-on: http://review.couchbase.org/34942
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>