Added style to make the text overflow of the datagrid footer elips

The footers text overflow elips the same as a cell does

A24group/Triage#3817

Test
 * Check this out
 * Compile jar
 * Copy jar to triage
 * deploy gwt
 * View a timesheet with the total expense longer that the length of the column. Make sure that the totals elips the same way as the cells