created upgrade script to version 3.1.4

- refactored app_controller's _checkDatabaseVersion
	- renamed to _checkSystemVersion
	- now checks system version number - assuming that when
	a database upgrade is needed, the system version number
	also increases
- changed sql script's database.version to 7 and system.version to
3.1.3 (current version). Need to update to 3.1.4 when the system is
bumped to 3.1.4
- refactored upgrade index view to show the current installed system
and database versions and the most recent versions.
- created an upgrade script soley for updating the system version.
This upgrade script will always be upgradable if the system version
in the core is higher than the one in the database.
	- removed the system version update from the upgrade base
	- added an additionaly logic to also make the system version
	upgrade script to be upgradable if the system.version parameter
	is not found.