Adding missing Anti-Xsrf token validations in some Post actions

1. Also adding this validation on a AJAX only used action.
[ValidateAntiForgeryToken] needs both the antixsrf cookie as well as the form body parameter named __RequestVerificationToken. Because there is no cookie in this context, the javascript code posts the xsrf token as a header. So the action has to validate it in this way. Here is a sample : http://www.asp.net/web-api/overview/security/preventing-cross-site-request-forgery-(csrf)-attacks. Checkout the "Anti-CSRF and AJAX" section.