Tweak installation tab. Add global navigation

git-svn-id: https://plugins.svn.wordpress.org/newsme/trunk@932954 b8457f37-d9ea-0310-8a92-e5e31aec5664
Add global nav to screenshot tab. Fix markdown in faqs for missing heading

git-svn-id: https://plugins.svn.wordpress.org/newsme/trunk@932956 b8457f37-d9ea-0310-8a92-e5e31aec5664