added an SSL related connection error
Merged in antti_haapala/sqlalchemy/antti_haapala/added-an-ssl-related-connection-error-1397245079299 (pull request #13)

added an SSL related connection error
- Added a new "disconnect" message "connection has been closed unexpectedly".
This appears to be related to newer versions of SSL.
Pull request courtesy Antti Haapala.