Add push/pull_all_files_from_path() tasks

[jambox]

Add two helper tasks to push/pull and files specified in the target.path key. Thanks @gyopiazza for the suggestion! Starter pseudo code:

grunt.registerTask("pull_all_files_from_paths",
  "Pull files from all directories defined in the path obj.",
  function () {

    if (local_options.path !== null && typeof local_options.path === 'object') {
      for (var key in local_options.path) {
        if( target_options.path[key] !== null ) {

          // Build config object with other necessary params

          // var config = {
          //   rsync_args: rsync_args,
          //   ssh_host: target_options.ssh_host,
          //   exclusions: exclusions
          // };
          // config.from = local_options.path[key];
          // config.to = target_options.path[key];
          util.rsync_push(config);
        } else  {
          grunt.fail.fatal('Trying to pull files files from target with no matching path for' + key + '!')
        }
      }
    } else {
      grunt.fail.fatal('Trying to pull files without a path object in config!')
    }

  }
);