allow minitest 5 and up.
require Cells::Layout in favour of AbC::Layouts.
use 4.0.2 for tests.
set the Layouts constant for all rails 3.0-4.0.
rename ::rails4_0_or_more? to ::rails4_0?.
fix tests.
include Layouts after the VersionStrategy.
introduce VersionStrategy for 4.1.
move rails3..? methods to RailsVersion. this will be deprecated in 3.10. the methods will still be available, but in a separate module.