app.js

angular.module('App').config(function (RestangularProvider) {

  // convert json request to x-www-form-urlencoded request
  RestangularProvider.setFullRequestInterceptor(function (el, op, what, url) {
    if (op === "put" || op === "post") {
      var res = "";
      _.forOwn(el, function (v, k) {
        if (!_.isFunction(v)) {
          res += k + "=" + encodeURIComponent(v) + "&";
        }
      });
      return {
        headers : { "Content-Type": "application/x-www-form-urlencoded" },
        element : res.substr(0, res.length - 1),
        params  : {}
      }
    }
    return {
      headers : {},
      element : el,
      params  : {}
    };
  });

});