Added 'from_conf()' method in the base measures store class as a abstract...

Added 'from_conf()' method in the base measures store class as a abstract class method to make sure that measure stores subclasses implement it

core/measures_store/__init__.py

@@ -55,6 +55,11 @@ class MeasuresStore(ABC):
     _MEASURE_GROUP_SEP = ':'
     #_MEASURE_GROUP_SEP_B = b'-'
 
+    @classmethod
+    @abstractmethod
+    def from_conf(cls, conf):
+        pass
+
     def __init__(self):
         pass