Trim whitespace from option .text() before concatenating into comma-separated button label

[zarino]

If the <option> elements have leading or trailing whitespace inside them, this is preserved when the button text is constructed by updateButtonContents.

This could be unexpected, because the browser would normally strip this leading and trailing whitespace when displaying elements like that. We should do the same.

Should be simple enough to turn line 194 from:

selected.push( $(this).text() );

Into:

selected.push( $.trim($(this).text()) );