Minor refactoring
Merge pull request #21 from SJApps/master

Google Image API implemented
Merge branch 'master' of https://github.com/dzenbot/DZNPhotoPickerController

Conflicts:
	Source/API/DZNPhotoServiceFactory.m
Constants rename/refactor
Added Service transform method from string. Refactored and reordered more constants implementations.
Renamed API folder
Renamed DZNPhotoServiceEndpoints to DZNPhotoServiceConstants
Synthesized values set to dictionaries
Enabled auto-completion search by setting Flickr's API the default and common service for all photo search clients.
Minor refactoring.
Added implementation class for DZNPhotoPickerControllerConstants to encapsulate external methods
Added search string to tag search result for Flickr
Added DZNPhotoPickerControllerServiceEdition enum
Fixed #23
Replaced sample Google consumer key and Google search engine id.
Added support for selecting different services orders, and single service as well.
Renamed DZNPhotoPickerControllerEdition to DZNPhotoPickerControllerSubscription
Updated access tokens and added Yahoo Images tokens
More refactoring on constants
Minor refactoring