Use taskflow library for building and executing action plans

The aim of this patchset is to integrate taskflow in
the Watcher Applier. Taskflow will help us a lot to make
Action Plan execution easy, consistent, scalable and reliable.

DocImpact

Partially implements: blueprint use-taskflow

Change-Id: I903d6509d74a61ad64e1506b8a7156e6e91abcfb
Closes-Bug: #1535326
Closes-Bug: #1531912

watcher/tests/applier/actions/loading/test_default_actions_loader.py

@@ -0,0 +1,32 @@
+# -*- encoding: utf-8 -*-
+# Copyright (c) 2016 b<>com
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import unicode_literals
+
+from watcher.applier.actions import base as abase
+from watcher.applier.actions.loading import default
+from watcher.tests import base
+
+
+class TestDefaultActionLoader(base.TestCase):
+    def setUp(self):
+        super(TestDefaultActionLoader, self).setUp()
+        self.loader = default.DefaultActionLoader()
+
+    def test_endpoints(self):
+        for endpoint in self.loader.list_available():
+            loaded = self.loader.load(endpoint)
+            self.assertIsNotNone(loaded)
+            self.assertIsInstance(loaded, abase.BaseAction)