support for additional headers / wss port

hi, 

i am using wss client to access a server which requires me to send credentials (basic). that involves adding headers to the request which the current interface does not allow. i have changed a few constructors by adding an additional parameter (with a default value to avoid breakage) which allows you to add any number of custom http headers to your request. that has worked very nicely for me so i thought i'd share it.

i have also changed the default port for wss in the tornado client from 80 to 443.