Don't run the skynet example from the tests.

It's too slow on the Travis bots and times out.

util/test.py

@@ -122,7 +122,7 @@ class Test:
       timed_out[0] = True
       p.kill()
 
-    timer = Timer(5, kill_process, [proc])
+    timer = Timer(2, kill_process, [proc])
 
     try:
       timer.start()
@@ -362,6 +362,9 @@ def run_example(path):
   if "animals" in path: return
   if "guess_number" in path: return
 
+  # This one is annoyingly slow.
+  if "skynet" in path: return
+
   run_script(WREN_APP, path, "example")