revert part of a previous merge which removes the Wnnn numbers showing so you could pick them up quickly

revert part of the 'cleanup' which removed this feature from grunt-contrib-jshint: *always* print the JSHint W/nnn/ error code (which speeds up the process of picking these up and adding specific error skip/ignore clauses in the JSHint config and/or sourcecode)

(And yeah, they are visible in 'grunt --verbose' mode, but that clutters the output no end for larger grunt runs.)