Updated readme to reflect changes in 0.5.6
Merge branch 'master' into svn

git-svn-id: https://plugins.svn.wordpress.org/papercite/trunk@855455 b8457f37-d9ea-0310-8a92-e5e31aec5664
Stable version is 0.5.7

git-svn-id: https://plugins.svn.wordpress.org/papercite/trunk@855456 b8457f37-d9ea-0310-8a92-e5e31aec5664