Strategy requirements

This patch set adds /state resource to strategy API
which allows to retrieve strategy requirements.

Partially-Implements: blueprint check-strategy-requirements
Change-Id: I177b443648301eb50da0da63271ecbfd9408bd4f

watcher/decision_engine/strategy/strategies/outlet_temp_control.py

@@ -77,6 +77,8 @@ class OutletTempControl(base.ThermalOptimizationBaseStrategy):
     # The meter to report outlet temperature in ceilometer
     MIGRATION = "migrate"
 
+    DATASOURCE_METRICS = ['host_outlet_temp']
+
     METRIC_NAMES = dict(
         ceilometer=dict(
             host_outlet_temp='hardware.ipmi.node.outlet_temperature'),