Allow to fork a repository in current namespace

Author: shulard

lib/Gitlab/Api/Projects.php

@@ -378,6 +378,15 @@ public function removeLabel($project_id, $name)
         ));
     }
 
+    /**
+     * @param int $project_id
+     * @return mixed
+     */
+    public function fork($project_id)
+    {
+        return $this->post('projects/fork/'.$this->encodePath($project_id));
+    }
+
     /**
      * @param int $project_id
      * @param int $forked_project_id