Hey bagas, subdirectories in the mixin directory is something we
overlooked. I have added it now, you won't need to make any changes to
your code, they should just load now.
I have pushed it to githum, but not released a new version yet. But I
will in the next fee days.
In the mean time, if your using bundled, just point it to the gizmo
git URL so it can install the gem from there.
I'll post another note when I push out the new version.