* DEV: Show warning message when using ember css selectors
When editing the theme css via the admin UI a warning message
will be displayed if it detects that the `#emberXXX` or `.ember-view`
css selectors are being used. These are dynamic selectors that ember
generates, but they can change so they should not be used.
* Update error message text to be more helpful
* Display a warning instead of erroring out
This allows the theme to still be saved, but a warning is displayed.
Updated the tests to check for the error message.
Updated the pre tags css so that it wraps for long messages.
395a903cf6