added gratipay donate

Author: pasupulaphani

README.md

@@ -2,7 +2,7 @@
 [![Build Status](https://travis-ci.org/pasupulaphani/simple-redis-store.svg?branch=master)](https://travis-ci.org/pasupulaphani/simple-redis-store)
 [![Coverage Status](https://coveralls.io/repos/github/pasupulaphani/simple-redis-store/badge.svg?branch=master)](https://coveralls.io/github/pasupulaphani/simple-redis-store?branch=master)
 [![dependencies Status](https://david-dm.org/pasupulaphani/simple-redis-store/status.svg)](https://david-dm.org/pasupulaphani/simple-redis-store)
-[![Donate to help support David development](http://img.shields.io/gratipay/pasupulaphani.svg?style=flat)](https://www.gittip.com/pasupulaphani/)
+[![Gratipay donate button](https://img.shields.io/badge/gratipay-donate-yellow.svg)](https://gratipay.com/simple-redis-store/)
 
 # simple-redis-store
 Redis store ready to scale with node-pool support