Link accounts by sending access token to auth methods.
Add unlink API call.
Use latest JWTDecode.
Add method to obtain identity for unlink.

The identity id has the format 'provider|user id'.
Update version to 1.0.0.
Merge pull request #31 from auth0/feature-link-account

Feature link account
Allow multiple connections inside A0Strategy.
Add A0Connection class.
Start using A0Connection instead of NSDictionary.
Cleanup A0Application interface.

Have a property for database strategy and another for all social ones.
Add strategy type to A0Strategy.
Filter strategies in application.
Add method to retrieve strategy by its name.