Fix #68: Add the CsrfHeaderMiddleware middleware to use custom HTTP header to prevent forgery of requests, add the CsrfMiddleware::withSafeMethods() method to configure a custom safe HTTP methods list

Fix #68: Add the CsrfHeaderMiddleware middleware to use custom HTTP header to prevent forgery of requests, add the CsrfMiddleware::withSafeMethods() method to configure a custom safe HTTP methods list #57