modifyAngularDefaultRequestContentTypeHeader.js

// The .config() part is the relevant part, 'SomeModule' is arbitrary name, 
// but this config() call goes on your main ng-app="YourAppModule"
// The PHP $_POST expects data w/ a form content type, not a JSON payload
angular.module("YourAppModule", ["SomeModule"]).config(function($httpProvider) {
  $httpProvider.defaults.headers.put['Content-Type'] =
    'application/x-www-form-urlencoded';
  $httpProvider.defaults.headers.post['Content-Type'] =
    'application/x-www-form-urlencoded';
});