Adding Project Skeleton.
Adding sales to installed apps.
Adding Base Model.
Adding Merchant Model.
Adding Item model.
Adding Sale model.
Adding Billing Model.
Adding Sales Models Tests.
Adding models import from txt feature.
Adding test sample.
Improving billing model.
Improving admin site.
Adding requirementes file.
Updating tests.

Once the billing model has been changed to automatically parse the
billing file the sale gerated by the test function is not the only sale
in the database anymore.
Adding project documentation.
Merge branch 'solution'