Fall back to GRAPH.QUERY when GRAPH.RO_QUERY is not available. (#124)

* `GRAPH.RO_QUERY` is unavailable in older versions. So fallback to
GRAPH.QUERY when the command is not found.

* Call the same method by setting read_only to `False`

Author: GnaneshKunal

redisgraph/graph.py

@@ -177,6 +177,9 @@ def query(self, q, params=None, timeout=None, read_only=False):
         except redis.exceptions.ResponseError as e:
             if "wrong number of arguments" in str(e):
                 print("Note: RedisGraph Python requires server version 2.2.8 or above")
+            if "unknown command" in str(e) and read_only:
+                # `GRAPH.RO_QUERY` is unavailable in older versions.
+                return self.query(q, params, timeout, read_only=False)
             raise e
         except VersionMismatchException as e:
             # client view over the graph schema is out of sync