1. modified code to show gravatar in all conditions. 
2. modified readme to explain requirements of this plugin.

git-svn-id: https://plugins.svn.wordpress.org/gmail-like-gravatar-fallback/trunk@1026716 b8457f37-d9ea-0310-8a92-e5e31aec5664
small code fix

git-svn-id: https://plugins.svn.wordpress.org/gmail-like-gravatar-fallback/trunk@1026718 b8457f37-d9ea-0310-8a92-e5e31aec5664