fix gen_service_plan issue

1. typo
2. require gen_service_plan in tool.rb
3. special handling of rabbitmq and vblob

Change-Id: Ifcf2ed209fff2f0f9b21ec88c6127ed06fde0223
Signed-off-by: michael zhang <zhangcheng@rbcon.com>
Reviewed-on: http://reviews.cloudfoundry.org/13029
Tested-by: CI Master <cf-ci@rbcon.com>
Reviewed-by: Pin Xie <pxie@vmware.com>