Add -v to docker-compose down to remove created volumes again (#32)

Author: maxstreese

testcontainers/compose.py

@@ -23,7 +23,8 @@ def start(self):
 
     def stop(self):
         with blindspin.spinner():
-            subprocess.call(["docker-compose", "down"], cwd=self.filepath)
+            subprocess.call(["docker-compose", "down", "-v"],
+                            cwd=self.filepath)
 
     def get_service_port(self, service_name, port):
         return self._get_service_info(service_name, port)[1]