WIP: 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.

## General

- [x] Finish styling the settings form.
- [x] Responsive tabs.
- [x] Form validation / error messages.
- [x] Close the form on save?
- [x] Increase the font-size of the schedule sentence.
- [x] Running backup status in schedule sentence.
- [x] Add schedule
- [x] Default schedule tab isn't highlighted
- [x] Enable support (still needs some TLC)
- [x] Running backup status in background tabs.
- [x] Allow upsell to be minimized / closed
- [x] Open upsell links in a new window
- [ ] Retina upsell icons
- [ ] Upsell for dev package
- [ ] Upsell needs some design TLC
- [x] Email service doesn't work
- [x] Integrate remote destinations
 - [ ] [Just waiting on Rackspace.](https://github.com/humanmade/backupwordpress-pro-rackspace/pull/1)
- [x] Show the timezone in the schedule sentence next scheduled time `title`
- [x] Change settings form to a single done button
- [x] Needs to work on 5.2

## Excludes

- [x] Excluded files should be greyed out
- [x] Exclude button should add an exclude rule for that exact path
- [x] Style the file list
- [x] Clicking a directory link should reload page with that path set as root
- [x] Ability to re-calculate any directory size
- [x] Ability to nagivate back up the tree
- [x] Design treatment for unreadable files
- [x] Show full path in title attribute
- [x] Switch to [Backdrop](https://github.com/humanmade/Backdrop/pull/4)
- [x] We need to way to track whether a directory tree is currently being analysed
- [x] Calculate site size should use the same mechanism, that way excludes tree will mostly already be cached
- [ ] Visually de-emphasise small files, especially in a long list (ala [Daisy Disk](http://www.daisydiskapp.com/))
![screen shot 2014-08-09 at 23 02 04](https://cloud.githubusercontent.com/assets/308507/3867782/d6f665ac-2010-11e4-823b-e113bcdfdd1c.png)
- [x] Done button for excludes form

## Javascript Progressive Enhancements

- [x] Show/Hide time fields depending on schedule in settings
- AYS Modals
 - [x] Delete schedule
 - [x] Delete backup
 - [x] Remove Exclude rule
- [x] Run schedule
 - [ ] Catch errors when backup fails.
- [x] Error popup when running a schedule
- [x] Live update schedule status
- [x] Calculate backup filesize
- [ ] Directory filesize

### Other (might be bumped to future)

- [ ] Unit tests
- ~~Properly calculate the total filesize of a wildcard exclude rule.~~

## Before launch

- [ ] Completely polished
- [ ] Thoroughly tested
- [ ] Unit tests pass
- [ ] No code todos