Initial commit
Starting out stuff
Adding nested relationship in form
Business logic
Adding phpunit test bootstrapper, and config check from framework
Refactoring some naming convention

* Item is now called a "Line", as it is in the context of a bill
* InventoryItemInterface is to map from a catalog (mock for now)
* LineImportedInterface is to differentiate an imported item than a normal item
* Added exception SubtotalNotCalculatedException, in case we did not calculate the subtotal
* TaxModel has now all calculation logic
Matching use case with specs
Illustrating three use cases
First unit tests, after creating the logic.

So much for TDD. :/
Ignoring SQLite file
Commiting unit tests. Incomplete, but gives an idea.
Adding README
Merging local workspace