Integration with grunt-contrib-watch

[mgenov]

grunt-contrib-jshint plugin already has such integration and it's integration is easy to be added.

Here is an example that could be used as sample for grunt-sync:

 // On watch events configure jshint:src to only run on changed file
  grunt.event.on('watch', function(action, filepath) {
    grunt.config('jshint.src', filepath);
  });