Cleaning + Session/DB Improvements

* Reorganized functions, moving all session/user queries outside of
Connection class.
* Added 'db_sync' to configuration options. Session will only sync with
database after exceeding this limit.
* Session view count in database now updates to the local session.
* Moved global (temp) salt into config
* Added Garbage Collection function to Connection. Currently removes
expired/inactive sessions.
* Added WIP admin page for viewing session information (in the future
will have basic CMS features).