AUI-1420 Form builder text fields overflow when width attribute has invalid value

Hi @jonmak08,

Attached is an update for https://issues.liferay.com/browse/AUI-1420.

The width of the text field is styled by the Bootstrap 3 .col classes defined in WIDTH_VALUES_MAP. Therefore, the width attribute should only have values defined in the WIDTH_VALUES_MAP object. I added a setter function in the width attribute to check this.

Please let me know if there's any issues. Thanks!