Try to re-pack long ints as strs

Refs test failures in integration.states.file.FileTest.test_managed_contents

salt/payload.py

@@ -119,7 +119,7 @@ class Serial(object):
         '''
         try:
             return msgpack.dumps(msg)
-        except OverflowError:
+        except (OverflowError, msgpack.exceptions.PackValueError):
             # msgpack can't handle the very long Python longs for jids
             # Convert any very long longs to strings
             # We borrow the technique used by TypeError below