Security request and Theme/Web UI builder

[dba61]

In the next release could you please make it so that simultaneous logins are not possible and that after being idle for a set time a user is automatically logged out.

Allow an administrator to set the number of IP Adresses that can use a single username. These two items would help make Subsonic a lot more secure.

Make these security features an option under settings so that the site adminstrator can use them if desired.

In a separate application please create a Theme and Web UI Builderso that people like me who do not program can still create a unique UI and theme for their users and share with the Subsonic community.