Fix rendering issue in Linux Chrome v38

The Chrome update made rows a tiny bit wider, so that non-fixed columns are forced to "wrap to the next line"... but the "next line" is below everything in the fixed columns! See http://stackoverflow.com/questions/26495735/google-chrome-rendering-floated-text-on-multiple-lines.

This is probably a hack, but forces the text not to wrap. This should be ok because ember-table computes and sets widths.