Multisite bug

Hello,

regular admin user (not super admin) on our WP Multisite was not able to open Settings -> Instant Articles.

We had to change “switch_themes” to “manage_options” in lhafb_theme_settings::add_theme_settings_page() where add_options_page() is called.

Please include this fix in next release. Github pull request created here: https://github.com/luehrsenheinrich/afb_instant_articles/pull/67

Thanks!