iTunes category and subcategory selection updated for latest iTunes category selection rules.

git-svn-id: https://plugins.svn.wordpress.org/powerpress/trunk@997314 b8457f37-d9ea-0310-8a92-e5e31aec5664
a couple more tweaks.

Updated readme.txt.


git-svn-id: https://plugins.svn.wordpress.org/powerpress/trunk@997317 b8457f37-d9ea-0310-8a92-e5e31aec5664