Removing media query on widget .settings-center class

- Removing this media query to stop forcing a fixed width when bootstrap breakpoint is medium or higher.
- Making this change because a widget settings page will sometimes require a lot of width real estate (eg. font setting component). If a widget settings page doesn't require a lot of width real estate than we can override in that particular widget settings own css.
Merge pull request #44 from stulees/chore/widget-settings-styling

Removing media query on widget .settings-center class