Inherit the class attribute when generating the table header's column.

Hi,

Was using ng-table and noticed that the td's class attribute are not getting read when generating the td's headers. For example:

< table ng-table.... >
 < tr..>
  < td ></td>
  < td class='visible-sm></td> 
< /tr>
< /table>

If the visible-sm class contains "display: none", it will hide the column data.
I wanted to hide the column header too.

Hope you can do something like this, and bump a new bower version soon.. :)

Thanks!!