title: Update Common AngularJS HTTP Headers at Runtime
body: <p>How can I update the common HTTP headers at runtime from an AngularJS controller, e.g. <code>$httpProvider.defaults.headers.common['Authorization']</code>? It seems <code>$httpProvider</code> can only be accessed from a config module, but I need to update common HTTP headers for all future requests from a controller, or a service called by the controller.</p>
  
  <p>I can update the locally scoped headers for the next request by injecting <code>$http</code> into my controller, but I need to do update HTTP headers for all future requests, specifically for basic authentication.</p>