Override shutdown method on _StandaloneSSLConnection object to strip "how" argument.
Override shutdown method on _StandaloneSSLConnection object to strip "how" argument.

Normal socket has "how" argument but OpenSSL.SSL.Connection doesn't. To avoid
an error, insert a function to remove the argument.

Bonus:
Quit if --tls-client-auth is specified but ssl module is not available.
We log that at critical level now but forgot to exit.
Review URL: https://codereview.appspot.com/7374048

git-svn-id: d23f85197b9dafcb1b1682eb9d0eda70517bdc52@730 4ff78f4a-9131-11de-b045-6380ec9940d4

bpsinc-native/src_third_party_pywebsocket_src,bpsinc-native/src_third_party_pywebsocket_src,bpsinc-native/src_third_party_pywebsocket_src,bpsinc-native/src_third_party_pywebsocket_src