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/goal/efficacy/base.py

@@ -0,0 +1,75 @@
+# -*- 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.
+
+import abc
+import json
+
+import six
+import voluptuous
+
+
+@six.add_metaclass(abc.ABCMeta)
+class EfficacySpecification(object):
+
+    def __init__(self):
+        self._indicators_specs = self.get_indicators_specifications()
+
+    @property
+    def indicators_specs(self):
+        return self._indicators_specs
+
+    @abc.abstractmethod
+    def get_indicators_specifications(self):
+        """List the specifications of the indicator for this efficacy spec
+
+        :return: Tuple of indicator specifications
+        :rtype: Tuple of :py:class:`~.IndicatorSpecification` instances
+        """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def get_global_efficacy_indicator(self, indicators_map):
+        """Compute the global efficacy for the goal it achieves
+
+        :param indicators_map: dict-like object containing the
+                               efficacy indicators related to this spec
+        :type indicators_map: :py:class:`~.IndicatorsMap` instance
+        :raises: NotImplementedError
+        :returns: :py:class:`~.Indicator` instance
+        """
+        raise NotImplementedError()
+
+    @property
+    def schema(self):
+        """Combined schema from the schema of the indicators"""
+        schema = voluptuous.Schema({}, required=True)
+        for indicator in self.indicators_specs:
+            key_constraint = (voluptuous.Required
+                              if indicator.required else voluptuous.Optional)
+            schema = schema.extend(
+                {key_constraint(indicator.name): indicator.schema.schema})
+
+        return schema
+
+    def validate_efficacy_indicators(self, indicators_map):
+        return self.schema(indicators_map)
+
+    def get_indicators_specs_dicts(self):
+        return [indicator.to_dict()
+                for indicator in self.indicators_specs]
+
+    def serialize_indicators_specs(self):
+        return json.dumps(self.get_indicators_specs_dicts())