Improve accessibility

 * Added role="rowheader" and scope="row" to the <th> elements in the
   first column
 * Remove tabindex from columns
 * Added scope="col" to <th> elements in <thead>
 * The label with the contents "search" was wrapping the <input>
   element. As a solution a label with a "for" attribute matching an ID
   on the <input> element was added to the markup.
 * Added a new group of controls for sorting the table in ascending and
   descending order to resolve the accessibility issues of the
   DataTables. When selecting an item from the drop down menu or
   switching the column headers in the DataTables triggers the same
   action or request as clicking the <th> elements to reorder the page.
 * Add label preceding "records per page" control.
 * Added "sAccessibility" parameter. This parameter enables
   accessibility (1) or disables it (0) in this JQuery
   plug-in library.