Added support for some authentication mappings scenarios

Enabled JwtSecurityTokenHandlerWrapper and HttpSaml2SecurityTokenHandler to work correctly when added together to a TokenHandlerCollection in an Authentication Mapping.
Added helper method for handler configuration that supports an encrypted SAML token.
Added helper method that enables one authentication mapping with both SAML2 and JWT handlers.
Enabled JwtSecurityTokenHandlerWrapper  to read a JWT token wrapped with WS-* xml.

see issues:
https://github.com/thinktecture/Thinktecture.IdentityModel.45/issues/133
https://github.com/thinktecture/Thinktecture.IdentityModel.45/issues/132
https://github.com/thinktecture/Thinktecture.IdentityModel.45/issues/113