Add a tests user to run unprivileged tests as; use it in devel/kyua.
This new user carries a generic 'tests' name because, even though it is
only used by devel/kyua at this point, it could conceivably be used by
Bump PORTREVISION of devel/kyua to 1.
Approved by: asomers (maintainer), bdrewery (ports), rpaulo (mentor)