Improve success rate of mustachification

imgtype=face tries to return results that contain human faces
making it easier for mustachify to do its job.

src/scripts/google-images.coffee

@@ -24,13 +24,15 @@ module.exports = (robot) ->
     if imagery.match /^https?:\/\//i
       msg.send "#{mustachify}#{imagery}"
     else
-      imageMe msg, imagery, (url) ->
+      imageMe msg, imagery, false, true, (url) ->
         msg.send "#{mustachify}#{url}"
 
-imageMe = (msg, query, animated, cb) ->
+imageMe = (msg, query, animated, faces, cb) ->
   cb = animated if typeof animated == 'function'
+  cb = faces if typeof faces == 'function'
   q = v: '1.0', rsz: '8', q: query, safe: 'active'
   q.as_filetype = 'gif' if typeof animated is 'boolean' and animated is true
+  q.imgtype = 'face' if typeof faces is 'boolean' and faces is true
   msg.http('http://ajax.googleapis.com/ajax/services/search/images')
     .query(q)
     .get() (err, res, body) ->