Added definitions for passport-strategy

To be able to implement different strategies in typescript for passportjs

The augmented functions are not available in the documentations but are taken from the source code: https://github.com/jaredhanson/passport/blob/master/lib/middleware/authenticate.js#L171

Hmm... It doesn't have any dedicated web-site.. 
Maybe the link to the github page is better: https://github.com/jaredhanson/passport-strategy
What do you think?