Extracted an interface for the Authorizer class to allow for user-customized authorization methods
Added authorizer javadoc
Included authorizer in the RealtimeOptions configuration
Moved authorizers into their own package
Added a separate Authorizer implementation to use Google Service accounts rather than user accounts.
Removed Google Service Account related code from the PromptAuthorizer
Merge pull request #31 from mkrause/authorization-refactoring

Authorization refactoring