Graphing refactor

Lots of changes that will address the current graphing system in MPOS:

* [ADDED] SQL table to store user statistics each statistics cron ron
* [REMOVED] Pool and Combined graphs since they don't work (yet) with the new system
* [ADDED] Admin setting to change the timeframe of the graph (default 1 Day/24 Hours)
* [CHANGED] Shares/second is now diff shares/second, means you see your diff inserted to the DB by one second passed
* [ADDED] Upgrade file and Base SQL File