toastergui fix size rendering in dirinfo page

We fix the rendering of the size field in dirinfo-related pages
by directly calling filtered_filesizeformat and not rendering
it through the template engine.

Additionally, we enable error dumping into logs if an
Exception happens.

[YOCTO #6669]

Signed-off-by: Alexandru DAMIAN <alexandru.damian@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>