add grep option to grunt test:unit

services/spelling/Gruntfile.coffee

@@ -31,6 +31,7 @@ module.exports = (grunt) ->
 			unit:
 				options:
 					reporter: grunt.option('reporter') or 'spec'
+					grep: grunt.option("grep")
 				src: ["test/unit/js/**/*.js"]
 
 	grunt.loadNpmTasks 'grunt-contrib-coffee'