Add manifold preview media type

Author: Evgeniy Guseletov

lib/Github/Api/Repository/Assets.php

@@ -11,6 +11,16 @@
  */
 class Assets extends AbstractApi
 {
+    /**
+     * @deprecated Will be removed as soon as gh releases api gets stable
+     */
+    public function configure()
+    {
+        $this->client->setHeaders(array(
+            'Accept: application/vnd.github.manifold-preview'
+        ));
+    }
+
     /**
      * Get all release's assets in selected repository
      * GET /repos/:owner/:repo/releases/:id/assets

lib/Github/Api/Repository/Releases.php

@@ -12,6 +12,16 @@
  */
 class Releases extends AbstractApi
 {
+    /**
+     * @deprecated Will be removed as soon as gh releases api gets stable
+     */
+    public function configure()
+    {
+        $this->client->setHeaders(array(
+            'Accept: application/vnd.github.manifold-preview'
+        ));
+    }
+
     /**
      * List releases in selected repository
      *