Get previous session if it exists
Get previous session if it exists

Instead of creating a new session each time
a user logs in, get their previous session if
they have one. That way, if a user does not
complete the survey they can still login and
complete their session.

CenterForOpenScience/isp,samanehsan/isp,samanehsan/isp,CenterForOpenScience/isp,samanehsan/isp,CenterForOpenScience/isp