Maj Readme + various improvements (see trello Df Wordpress Plugin)

git-svn-id: https://plugins.svn.wordpress.org/dialogfeed/trunk@992420 b8457f37-d9ea-0310-8a92-e5e31aec5664
Improve readme prez for wordpress.org

git-svn-id: https://plugins.svn.wordpress.org/dialogfeed/trunk@992424 b8457f37-d9ea-0310-8a92-e5e31aec5664