Change `secureOptions' to `secureProtocol' for HTTPS request

to meet the nodejs https module
see: http://nodejs.org/api/https.html#https_https_request_options_callback
add `ciphers' and `secureProtocol' to `options' in `getAgent'

to make them really work
Merge pull request #666 from richarddong/master

make `ciphers` and `secureProtocol` to work in https request