Add and (almost) edit expenses
Implementing CoreData
Works with GroupList
Doesn’t work with group yet
Revert b06d4f6..ea7726f

This rolls back to commit b06d4f6bbd6de83d173ec01b244e8d6032014e04.
Summary, loadtime

Summary shows old balance, changes and new balance
Page waits for loaded data before showing it
Merge branch 'show-list-of-expenses'