Sorting.
Added sorting tests.
Updated snapshots.
Merge pull request #105 from AshFurrow/sorted

@orta => Added sorting capability to listings view controller
RAC for current bid, opening bid, bid validation
Merge pull request #106 from 1aurabrown/bid-validation

@ashfurrow => RAC for current bid, opening bid, bid validation
Bumped Moya to 0.5.
Merge pull request #108 from AshFurrow/moya-update

@orta => Bumped Moya to 0.5.