Use Device.js to determine mobile editor use

Ref #2570
- Adds new library, device.js to determine if the user is on an ios mobile
  or tablet.
Better handling of validation errors + more documentation

closes #3153
- this is all about the validation engine
- add a option, `opts.model`, to use a passed-in model directly if needed
- handle validators that return an array of strings, array of objects, or both
- ajax util returns either an array of errors or a single concat'd string
- remove formatErrors function from the mixin and make it private
- allow validation options to be passed into `.save()` since ember-data doesn't take params on `.save()` anyway
- streamline control flow
Merge pull request #3154 from darvelo/validation-update

Better handling of validation errors + more documentation
Replace the old admin with the ember admin

closes #3056

- Remove clientold
- Remove clientold tests
- Cleanup old admin helpers
- Remove old routes from admin and controllers from admin controller
- Comment out / remove old and broken tests
- Cleanup Gruntfile.js, bower.js, package.json etc

Still TODO:

- cleanup / add removed tests
- do we still need countable?
Merge pull request #3157 from novaugust/device

Use Device.js to determine mobile editor use
Merge pull request #3165 from ErisDS/issue-3056

Replace the old admin with the ember admin