Federation: Login on distant server - Session duration

Not sure if it's server side or client side though. Need digging.

Related: djangoldp-packages/djangoldp-account#43 (closed)

Context: When I login on test2's server with my user on test1, after a while (~15mn), I get logged out on front-end, but I'm still logged in on test1 server.

@balessan Don't know what to do with this one, here's a gift for you. :)