* item model (contains basic item info, similar to the gx version)
* module model (has info about each module and which version of it is installed)
* added a very basic unit test to verify that we can create an instance of item
* Updated our test controller to require a unit_test db config and
call core::install if it hasn't been done already.
New pattern:
* core/helpers/core_installer.php creates core_installer helper.
When we install a new module you call xxx_installer::install(),
and when you want it to go away, you do xxx_installer::uninstall()
Create
