Qt metrics v0.16: Ajax loading animation added

Added a gif animation to show that the Ajax loading is in progress.
It will show next to "Loading..." text in metrics boxes. Purpose is
to show that the page is not stuck even though the first time loading
may take time.

Change-Id: Ic4ddda9b417edd383cbe53fb9a1aee0d2197f892
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>