Merge branch 'master' into expense-debt-payment
add better_errors gem
 add unique index to join table grocery_lists_suscribers
add routes for suscribing, unsuscribing, creating expense from grocery list
add unsuscribe and suscribe routes to grocery_lists_controller
add new_from_grocery_list route to expenses controller
add buy and suscribe buttons
add form to create expense from grocery list data
merge with master
solve merge conflict
remove unecessary test
update total_cents field to work with cents
Merge pull request #51 from purple-martins-2013/list-to-expense

List to expense