Move recipe engine to third_party/recipe_engine.

scripts/slave/recipe_modules/swarming_client/api.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.
 
-from slave import recipe_api
-from slave import recipe_util
+from recipe_engine import recipe_api
+from recipe_engine import recipe_util
 
 
 class SwarmingClientApi(recipe_api.RecipeApi):
   """Code that both isolate and swarming recipe modules depend on.
 
   Both swarming and isolate scripts live in a single repository called
   'swarming client'. This module include common functionality like finding
   existing swarming client checkout, fetching a new one, getting version of
   a swarming script, etc.
   """
@@ skipping 104 matching lines @@
       # TODO(martiniss) remove once recipe 1.5 migration done
       step_result = self.m.python.inline(
           '%s is too old' % script,
           'import sys; sys.exit(1)',
           add_python_log=False)
       # TODO(martiniss) get rid of this bare string.
       step_result.presentation.status = self.m.step.FAILURE
       step_result.presentation.step_text = abort_reason
 
       raise self.m.step.StepFailure(abort_reason)