Changes to Saml2Client for adding - NameIdPolicyFormat and AuthnContextClassRef when building SAMLRequest 

I have made the changes to incorporate the following in SAMLRequest:
-  <b>NameIdPolicy</b><br/>
Example : `<saml2p:NameIDPolicy
        Format="urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress"
        AllowCreate="true"></saml2p:NameIDPolicy>`
- <b>AuthnContextClassRef when using Comparison Type</b> <br/>
Example: ` <saml2p:RequestedAuthnContext Comparison="exact">
        <saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport</saml:AuthnContextClassRef>
    </saml2p:RequestedAuthnContext>`