Delete empty mojo python package, and prefix all python packages with mojo_

mojo/python/tests/mojo_unittest.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import unittest
 
 # pylint: disable=E0611,F0401
-import mojo.embedder
-import mojo.system
+import mojo_embedder
+import mojo_system
 
 
 class MojoTestCase(unittest.TestCase):
   def __init__(self, *args, **kwargs):
     unittest.TestCase.__init__(self, *args, **kwargs)
     self.loop = None
 
   def run(self, *args, **kwargs):
     try:
-      mojo.embedder.Init()
-      self.loop = mojo.system.RunLoop()
+      mojo_embedder.Init()
+      self.loop = mojo_system.RunLoop()
       unittest.TestCase.run(self, *args, **kwargs)
     finally:
       self.loop = None
-      assert mojo.embedder.ShutdownForTest()
+      assert mojo_embedder.ShutdownForTest()