All list returns in DiningSession, Menu, Order, Restaurant return deep
copies. Restaurant has menus stored in a Map (with appropriate methods)

Dining Session has new fields for storing users, start and end times,
and a checked in flag
Made a few changes to the styles and implemented onSaveInstanceState and
OnRestore Instance State.
Merge pull request #35 from blasv/class_skeletons_zach

Made most changes to the skeletons. No fields fully immutable right now
Merge pull request #36 from espeo196/master

onSaveInstanceState & onRestoreInstanceState