Added methods to transfer a project to another group. Fixes #9

Author: m4tthumphrey

lib/Gitlab/Api/Groups.php

@@ -24,4 +24,9 @@ public function create($name, $path)
             'path' => $path
         ));
     }
+
+    public function transfer($id, $project_id)
+    {
+        return $this->post('groups/'.urlencode($id).'/projects/'.urlencode($project_id));
+    }
 }

lib/Gitlab/Model/Group.php

@@ -49,4 +49,11 @@ public function show()
 
         return Group::fromArray($this->getClient(), $data);
     }
+
+    public function transfer($project_id)
+    {
+        $data = $this->api('groups')->transfer($this->id, $project_id);
+
+        return Group::fromArray($this->getClient(), $data);
+    }
 }