Add Codesponsor.io link

Author: mikenicholson

README.md

@@ -183,3 +183,7 @@ To generate test-coverage reports:
 The [MIT License](http://opensource.org/licenses/MIT)
 
 Copyright (c) 2015 Mike Nicholson
+
+<a target='_blank' rel='nofollow' href='https://app.codesponsor.io/link/wkA4NAa5HS7HRsfBixR5saSs/themikenicholson/passport-jwt'>
+  <img alt='Sponsor' width='888' height='68' src='https://app.codesponsor.io/embed/wkA4NAa5HS7HRsfBixR5saSs/themikenicholson/passport-jwt.svg' />
+</a>