Adding initial interface for backend and redis pubsub (#19)

* Adding initial interface for backend and redis pubsub

* Addressing comments, adding super in all memories

* Removing distributed experience replay

rl_coach/memories/backend/memory.py

@@ -0,0 +1,36 @@
+
+
+class MemoryBackendParameters(object):
+
+    def __init__(self, store_type, orchestrator_type, run_type, deployed: str = False):
+        self.store_type = store_type
+        self.orchestrator_type = orchestrator_type
+        self.run_type = run_type
+        self.deployed = deployed
+
+
+class MemoryBackend(object):
+
+    def __init__(self, params: MemoryBackendParameters):
+        pass
+
+    def deploy(self):
+        raise NotImplemented("Not yet implemented")
+
+    def get_endpoint(self):
+        raise NotImplemented("Not yet implemented")
+
+    def undeploy(self):
+        raise NotImplemented("Not yet implemented")
+
+    def sample(self, size: int):
+        raise NotImplemented("Not yet implemented")
+
+    def store(self, obj):
+        raise NotImplemented("Not yet implemented")
+
+    def store_episode(self, obj):
+        raise NotImplemented("Not yet implemented")
+
+    def subscribe(self, memory):
+        raise NotImplemented("Not yet implemented")