Adding Exponent and Modulus members to the JWKS Document

Added code so that the Exponent (e) and Modulus (n) members are added to the JWKS Discovery Document.  This brings the code into conformance with with [Section 4.2.2 of the JSON Web Key (JWK) Spec](http://self-issued.info/docs/draft-jones-json-web-key-00.html#anchor8), where the Exponent and Modulus members must be present if the algorithm is RSA.