Proposed changes for g5k client SSL mode.
These changes makes it possible to use python-grid5000 in a Grid'5000 trusted client.
The trusted client connects using a a SSL client certificate produced by Grid'5000, and push user info through the X-API-User-CN
and X-Remote-Ident
http headers.
The values for these headers can be provided through the g5k_user
argument to most function. If not the provided this value defaults to anonymous
.
The code was also made compatible with python2.7.