Fix code formatting
Fix state_changes to be destroyed when the associated order is destroyed
Refactor Spree::Order#associate_user! code and specs to be simpler

* Expand the specs to test all possible code paths. This code is fully
  mutation covered by mutant.
Change Spree::Order#associate_user to copy address information
Merge pull request #29 from MountainRoseHerbs/fix-address-population

Fix address population
Fix code formatting
Remove unused method from Spree::OrderUpdater
Add validations to Spree::Order

* This focuses most on improving the existing validations and adding
  validations for the totals that are updated based on user input.
[WIP] Change Spree::OrderUpdater#persist_totals to validate the totals

* If the totals are greater than the database columns can store, then we
  should avoid hitting the database and report the error.