title: ngResource custom headers when calling action
body: <p>In ngResource action I can specify custom request headers. However I need to set the headers at the time of calling the resource action.</p>
  
  <p>The reason is I need paging and sorting data for the list query, and those need to be specified by custom headers (X-Order, X-Offset, and so on). This data can vary from call to call, so I cannot have them in the resource action definition.</p>
  
  <p>Is there a way to pass headers while calling the action? (other than setting $http defaults)</p>