Added Twitter.framework to the test target.
[iOS SDK] Added a block-based interface to SinglyService for handling logins.
Cleanups to the Facebook and Twitter service implementations.
Added block-based subclasses of UIActionSheet and UIAlertView (internal only) to clean up and simplify some of the core project code.
Added protocol for providing the Twitter account to authorize when the device is signed in to more than one account.
Implemented a default Twitter account picker for SinglyLoginPickerViewController.
Made the SinglyService delegates optional (now that we have also block-based method signatures).
Use the new SinglyAlertView class throughout.
Significantly improved documentation for SinglyFacebookService.
Documentation and comment improvements.
Defined types for all of our blocks.
Added support for removing Singly accounts by calling `removeAccount:` or `removeAccountWithCompletion:` on the shared SinglySession instance.

This will destroy the account at Singly, disconnecting the user from
all services.
Fixed auth for the Facebook service.
Add Twitter.framework to the documented list of dependencies.
Improved the Facebook authorization workflow (closes #77).
Handle web view errors in the login view controller (closes #61).
Always return the response JSON from SinglyConnection, even in the case of errors.
Automatically renew credentials on Facebook token errors.
Pass original Singly response along with connection errors.
Fixed an issue where errors were not being passed through to applyService in some cases.