1. Added copy constructor for TokenValidationParameters
2. Fixed broken tests
3. Modified IdentityComparer to reduce code redundancy
4. Saml1 and Saml2 ReadToken marked override rather than virtual
5. AudienceValidator throws SecurityTokenInvalidAudienceException
6. Added shell for IExpirableNonceCache
Merge pull request #8 from brentschmaltz/dev

1. Added copy constructor for TokenValidationParameters