Restore compatibility with Python 2.6 in HTTPS cls

Fixes grnet/kamaki#73

The problem is caused by the argument "source_address' when
instantiating "httplib.HTTPSConnection" in "kamaki.clients.utils.https"
This argument was added in Python 2.7, therefore a TypeError would
ensue with Python 2.6
This is fixed by catching the TypeError and retrying without the
"source_address" argument.