Use except x as y instead of except x, y

According to https://docs.python.org/3/howto/pyporting.html the
syntax changed in Python 3.x. The new syntax is usable with
Python >= 2.6 and should be preferred to be compatible with Python3.

Enabled hacking check H231.

Change-Id: I4c20a04bc7732efc2d4bbcbc3d285107b244e5fa

launch/utils.py

@@ -188,7 +188,7 @@ def ssh_connect(ip, username, connect_kwargs={}, timeout=60):
         try:
             client = SSHClient(ip, username, **connect_kwargs)
             break
-        except socket.error, e:
+        except socket.error as e:
             print "While testing ssh access:", e
             time.sleep(5)