Close watchers to ensure handle is released. Fixes GH-79.
Close watchers to ensure handle is released. Fixes GH-79.

gruntjs/grunt-contrib-watch,AlexJeng/grunt-contrib-watch,yuhualingfeng/grunt-contrib-watch,eddiemonge/grunt-contrib-watch,testcodefresh/grunt-contrib-watch,Rebzie/grunt-contrib-watch,whisklabs/grunt-contrib-watch,JimRobs/grunt-chokidar,mobify/grunt-contrib-watch,Ariel-Isaacm/grunt-contrib-watch,chemoish/grunt-contrib-watch