Added efficacy specification to /goals

In this changeset, I added the new Efficacy, EfficacySpecification
and IndicatorSpecification classes which are the main components for
computing an efficacy.

Partially Implements: blueprint efficacy-indicator

Change-Id: I3a1d62569de2dd6bb6f9a52f6058313fa2b886ce

watcher/decision_engine/solution/efficacy.py

@@ -0,0 +1,27 @@
+# -*- 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 watcher.common import utils
+
+
+class Indicator(utils.Struct):
+
+    def __init__(self, name, description, unit, value):
+        super(Indicator, self).__init__()
+        self.name = name
+        self.description = description
+        self.unit = unit
+        self.value = value