title: How to intercept $resource requests
body: <p>Would there be a way to intercept requests in the $resource call? </p>
  
  <p>I want to add an OAUTHv2 header to it, instead of specifying this for every resource model.</p>
  
  <p>Currently I'm only able to intercept the <em>response</em>, as stated in the docs:</p>
  
  <blockquote>
    <p>...</p>
    
    <p>interceptor - {Object=} - The interceptor object has two optional
    methods - response and responseError. Both response and responseError
    interceptors get called with http response object. See $http
    interceptors.</p>
  </blockquote>
  
  <p>I know you can push a global interceptor on $http, but I don't want to include my Bearer token in any request outside API calls (security...)</p>
  
  <p>Anybody who is doing OAUTHv2 must have come across this problem. A pity there is no standard way in Angular.JS...</p>