Querying for sessions

[Les Hazlewood <lh...@apache.org>]

Just a note to those interested in Session operations - Querying for
sessions is a feature I've implemented in many of my Shiro-based
applications and it is very useful.  I think it would be a 'killer
feature' for Shiro and I'm sure a lot of people will find value in it.
 This will allow those who want to use this feature to ask/do:

- Is user X currently logged in?
- How many users are currently using the application?
- If user X already has a session, we can prevent new sessions for
that user, or,
- If user X creates a new session, invalidate all of their previous
currently open sessions.
maybe more...

The issue to track this is here:

https://issues.apache.org/jira/browse/SHIRO-117

Please add any comments if there are things you think might be
valuable that I haven't already covered.

Regards,

Les