Correct y axis print head size for printrbot simple

Print head size settings for printrbot simple had y min and y max mixed up,
making "print one at a time" always print in the wrong order.

resources/definitions/printrbot_simple.def.json

@@ -26,10 +26,10 @@
         "machine_nozzle_cool_down_speed": { "default_value": 2 },
         "machine_head_with_fans_polygon": {
             "default_value": [
-                [ 55, -20 ],
-                [ 55, 99999 ],
-                [ -49, 99999 ],
-                [ -49, -20 ]
+                [-49, 20],
+                [-49, -99999],
+                [55, 20],
+                [55, -99999]
             ]
         },
         "gantry_height": { "default_value": 99999 },