refactor codeclimate smells

[squidgetx]

• CartValidations
• ApplicationController
• Reservation
• User (Move LDAP into a module #1093)
• UsersController
• EquipmentImport (Refactor import functionality #899)
• ReservationsScopes (this one is only bad because in order to have the scopes in a separate file it all has to go into a method so CodeClimate tags it as a hugely complex method. however, if the actual reservation model is cleaned up enough we might be able to put the scopes back in. trying to deal with this using Concerns, see Refactor Reservation Scopes / Validations #1288)

[orenyk]

I like this as a bucket list, but we should probably have separate issues for each for version tracking purposes. Either that or get all of the refactoring into one release :-P.