Changed the Travis-ci image in README to point to Greg Bell's repo

Author: gregbell

README.rdoc

@@ -4,7 +4,7 @@ Active Admin is a framework for creating administration style interfaces. It
 abstracts common business application patterns to make it simple for developers
 to implement beautiful and elegant interfaces with very little effort.
 
-http://travis-ci.org/pcreux/active_admin.png
+http://travis-ci.org/gregbell/active_admin.png
 
 == Goals