fix Gsi authentication

- extend printing of UserInfo
- fix filling the variables for gsi auth from the proxy
fix dmlite auth and fill in headnode write methods

add working function bodies to the rm, rmdir, mkdir, write, .. functions.
the write function now only has the headnode part, so in redirects on
every request.

fix the connect() function of the dmlite_connection to correctly pass
authentication info to dmlite.