[backend] Various layout fixes.

I keep them separated until you guys have valuated them, then I can squash them.

- Fixes outdate jQuery live.
- Remove colons for label tags for consistency in layout.
- Add missing required for field in prototypes form.
- Fixes taxon form layout issues + js permalink helper.
- Remove loose p-tag in taxonomies index page.
- Nicer products stock delete icons.
- Fixes wild placed sorting icons.
- Misc table layout styling + cleanup in those files touched.

Also the jQuery UI autocomplete on product properties page is wild and un-styled, the quick CSS fix I use in my admin overrride:

```scss

.ui-widget {
  font-family: $base-font-family;
  font-size: 90%;
  font-weight: 400;
}

.ui-widget-content {
  background-image: none;
  border: 1px solid $color-border;
  -webkit-border-radius: 3px;
  -moz-border-radius: 3px;
  border-radius: 3px;
  color: $color-4;
  font-size: 90%;
}

.ui-autocomplete {
  width: 300px; /* fix width for product properties table */
  list-style-type: none;

  li {
    padding: 8px;

    .ui-corner-all {
      padding: 4px;
    }

    .ui-state-focus {
      background-image: none;
      background-color: transparent;
      color: $color-2;
      border: none;
      cursor: pointer;
    }
  }
}
```
...but no clue where it should go in the scss files so you welcome to copy and paste it where it belongs or give me directions where to put it.