Make  private to fix uninstall bug: https://easydigitaldownloads.com/support/topic/error-on-uninstall-uninstall-fails/#post-46770
add span.edd_empty_cart to empty cart message. Closes #1098
Merge branch 'master' of git://github.com/pippinsplugins/Easy-Digital-Downloads
Take 2 for adding an Extensions Settings tab