Introduced ApiKeyAuthenticationDispatcher.
Implemented the AuthServiceFactory property.
Implemented Principal.
Implmented ApiKeyAuthenticationDispatcher.
Addressed guard clause.
Renamd Principal to SimplePrincipal.
Addressed code-analysis errors.
Addressed the type 'Guid' of the parameter 'apikey' of FindUserAsync.
Merge pull request #14 from jwChung/api-key-authentication-dispatcher

Api key authentication dispatcher