Add use_session argument to request method.
Add use_session argument to request method.

This allows usage of an existing session to make a request with the
request and the get, post etc. function.

revolunet/requests,dvska/requesocks,psf/requests,msabramo/requests,revolunet/requests,abueesp/requesocks,Bluehorn/requests,hph86/requesocks