Re-design

There are several issues with the current backups admin page:

* It doesn't work without JS.
* Modals are not for settings.
* The modals are tiny, cramped and totally non-WordPress standard.
* Switching between the schedules is not as obvious as it could be.
* It doesn't work very well on mobile

We need to redesign how the settings flow works. It should:

* Work without JS
* Be more inline with WordPress standard styles
* Death to all modals
* Be responsive

This will effect the general schedule settings modal as well as those for adding a new schedule, managing excludes and enabling support. Our pro add-ons will also need updating to match the new setup.