 cell data in cell's title attribute.
    * Inputs:      object:oSettings - dataTables settings object
    *              array: aoColumnMaxChars - an array, element 0 being left most, containing a positive integer or null for each column.
    *              Null means do not truncate column, positive integer means to only allow that many characters to display in the column text. 
    *
    * Returns:     JQuery
    * Usage:       $('#example').dataTable().fnTruncateCells();
    * Requires:   DataTables 1.7