ACS Integration: Replace SWT with JWT using built-in .NET 4.5 WIF
 * Remove obsolete OAuthSecurity solution
 * Remove custom SWT handlers from Global.asax.cs files
 * 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
 * Streamline auth handlers/claim retrieval
 * Cleanup web.config tokenization/transforms