Addresses #220 - Adds multi-support for client server version match checks

flatland/evaluators/service.py

@@ -294,8 +294,12 @@ class FlatlandRemoteEvaluationService:
         _command_response = {}
         _command_response['type'] = messages.FLATLAND_RL.PONG
         _command_response['payload'] = {}
-
-        if client_version != service_version:
+        SUPPORTED_CLIENT_VERSIONS = \
+            [
+                flatland.__version__,
+                "2.1.5"
+            ]
+        if client_version in SUPPORTED_CLIENT_VERSIONS:
             _command_response['type'] = messages.FLATLAND_RL.ERROR
             _command_response['payload']['message'] = \
                 "Client-Server Version Mismatch => " + \