Widths of issue navigator columns controlled by CSS style sheet

Widths of issue navigator columns controlled by CSS style-sheet.

With access to the style sheet it is now quite trivial to customise the column widths and layouts as appropriate for your installation.

For example JRA-4527. It's now trivial to add a style:

td.assignee
{
white-space: normal;
}

td.reporter
{
white-space: normal;
}

In order to force the assignee & reporter fields to wrap.