Test results are listed on a series view. Some of them are expandable if
you click anywhere on their grey background.

This is not obvious and it's not indicated in any way.

This patch adds a triangle pointing down in the left corner to imply
this expand/collapse behavior.

The triangle starts pointing up when the section is expanded to indicate
that it is collapsible now.

Closes #35



Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>