Add 'Add New' buttons to edit links, edit media, and edit user screens. props...

Add 'Add New' buttons to edit links, edit media, and edit user screens. props sbressler, fixes #17499.

git-svn-id: https://core.svn.wordpress.org/trunk@17975 1a063a9b-81f0-0310-95a4-ce76da25c4cd