First pass at sync.
Fixes return-nil problem.
Merged upstream.
Merge branch 'master' of github.com:artsy/eidolon into sync

Conflicts:
	Kiosk/Auction Listings/ListingsViewController.swift
Merge pull request #166 from orta/placingbid

@ashfurrow => Polish
Merge branch 'master' of github.com:artsy/eidolon into sync

Conflicts:
	Kiosk/Auction Listings/ListingsViewController.swift
Pagination completed.
Update method returns success/failure and abstracted the sync interval into a property.
No longer syncs when presenting another view controller.
Fixed ListingsViewControllerTests.
Added tests for syncing.
Added error-handling on API call.
<= mixup oops.
Reverted to Moya change.
Fixed problem with <= in pagination code.
Merge pull request #125 from AshFurrow/sync

@1aurabrown => Sync ⛵
merge