Azure ACS: Replace clunky SWT integration with simpler JWT
ACS Integration: Replace SWT with JWT using built-in .NET 4.5 WIF
 * Remove custom SWT handlers/etc
 * Add JSON Web Token package from NuGet
 * Update web.configs for use with JWT Relying Party setup in ACS
 * Replace method for retrieving nameidentifier claim from HttpContext

TODO:
 + Restore AuthN/AuthZ request handlers
 + Tokenize updated web.configs
 + Create JWT RPs in ACS for integration/prod/etc