Fix mem_limit and memswap_limit regression

Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>

compose/service.py

@@ -42,6 +42,8 @@ DOCKER_START_KEYS = [
     'net',
     'log_driver',
     'log_opt',
+    'mem_limit',
+    'memswap_limit',
     'pid',
     'privileged',
     'restart',
@@ -684,6 +686,8 @@ class Service(object):
             restart_policy=restart,
             cap_add=cap_add,
             cap_drop=cap_drop,
+            mem_limit=options.get('mem_limit'),
+            memswap_limit=options.get('memswap_limit'),
             log_config=log_config,
             extra_hosts=extra_hosts,
             read_only=read_only,