Implemented Item domain
Finished implementing Item domain
Implemented User domain
Implemented first test with PHPUnit
Remove sings.ini from source control
Updated @todo items in test
Updated Sings defines and fixed unit tests

The Sings defined lead to a non-overwritable config file location which
is bad for testing. The mysqli->bind_param() and
mysqli->bind_result() parameters are updated because they need to be
passed by reference. The unit tests now have a decent bootstrap and some
minor issues that arose were fixed.