API: Clean up JSON response serialization
 * Refactor/consolidate response building/writing
Merge branch 'master' of https://github.com/RareCrowds/OpenAdStack
Merge branch 'master' of https://github.com/RareCrowds/OpenAdStack
Auth: Remove ineffective custom identityModel config from ApiLayer's web.config
WebLayer: Clean up 401/auth redirect handling
 * Translate ACS redirects to 401 responses in the API layer
 * Handle API 401 responses in js by redirecting to website root
 * Website root then redirects to ACS which redirects to login

Note: Static content does not redirect because it is not handled by .NET. To change this httpHandler entries can by added to handle .html with System.Web.UI.PageHandlerFactory