Fixing Cannot call method 'call' of undefined

Hello,

I used the *.add* method like that:

	watcher.add([file])

and I got 

	...gaze\lib\gaze.js:387
	      done.call(self, null, self);
	           ^
	TypeError: Cannot call method 'call' of undefined
	    at null._onTimeout (D:\work\KrasimirTsonev\github\absurd\node_modules\gaze\l
	ib\gaze.js:387:12)

_initWatched method expects a callback. If you miss that you end up with the above error.