Some fields in LegacyExpense where not mass-assignable

Set them manually
Needed to save certain attributes after record creation
Reactivated timestamp processing, added single test method
Added code for nil created_on dates
Added timstamp processing

User creates other records like groups and group_membershipts, timestamp
needs to be on for that portion
Added nil created_on processing, fixed a validation
Added more testing tasks, clear up the timestamp issue
Make validation work, include exceptions
Removed unused method
Fixed issue with LegacyExpense not seing class variable

changed from class variable to constant
Updated gems with bundle update
Updated todo
Added ability to call binding.pry to debug easier
Added LegacyUserPayment to import
Prepare for next single_import