Added classes for MenuItem, ListItem, and Receipt
Reordered classes to group by similarity
Added __repr__ to LineItem
Added return to MenuItem.__repr__ and LineItem.__repr__
Fixed tabs not being spaces
Expanded LineItem and Receipt
Added __str__() to Receipt and created tester
Comma in LineItem.line_total() formatting, corrected variable for receipt total
Merge branch 'master' into Josh

Conflicts:
	restaurant/models.py
Merge branch 'master' into Josh

Conflicts:
	restaurant/models.py
added receipt.total changed tax calculation to integers
Merge branch 'master' into Josh
added tip and add_tip and expanded __str__ for receipt