(feat) add a new module: Flickr

(feat) add a new module: Flickr
(fix) change the pathFunc in order to allow different callback names
(fix) modeules comment

I tested it with my own oauth proxy in php, but I don't see any reason why it shouldn't work with auth-server.js

I'll send another pull request that move the following check:
```javascript
if("jsonp" in o){
	o.jsonp(p,qs);
}
```
right after the if-block ```if( p.method === 'post' ){``` so the providers who need to change the callback name will be able to delete the previous callback instead than having 2 callbacks. You'll decide about accepting it.