Update pox to use uzip
Update pox to use uzip

Update pox to use the uzip package for zip instead of finding zip in the
PATH.

Signed-off-by: pallaud <b082fa5730a206bd76814081e36ac7690c120306@google.com>

hugelgupf/u-root,hugelgupf/u-root,u-root/u-root,u-root/u-root,hugelgupf/u-root,hugelgupf/u-root,u-root/u-root