Marshal eventContext

[will-moore]

As discussed in web api meeting:

Currently we are manually marshalling the eventContext as a json response to user login.
Would be nice if omero-marshal could handle this.

[will-moore]

Currently I'm doing this, but only as a response to successful Login. So, sessionUuid is not available from a GET request.

        c = conn.getEventContext()
        ctx = {}
        for a in ['sessionId', 'sessionUuid', 'userId', 'userName', 'groupId',
                  'groupName', 'isAdmin', 'eventId', 'eventType',
                  'memberOfGroups', 'leaderOfGroups']:
            if (hasattr(c, a)):
                ctx[a] = getattr(c, a)