Grunt: Clean up outdated information

* Use jshintrc:true which lets grunt defer autodiscovery of the file
  to jshint instead of forcing it to '.jshintrc'. This also us to
  override certain settings from a subdirectory, to match behaviour
  of standalone jshint.

* Remove comments about "Known issues" in node-jscs, those have
  been fixed a while back and were applied when we updated jscs
  in df8c455.

* Match load order.

* Use plain string instead of single-value array.

Change-Id: I7fd8db63ba164de705239c4b419de446ca7d6809