Specific /usr/local/bin/hus-cmd rootwrap filter

Add a specific filter for /usr/local/bin/hus-cmd, rather than adding
/usr/local/bin to the list of exec_path in rootwrap.conf. This allows to
sync rootwrap directly from oslo-incubator without having to edit the
default value for exec_dirs.

Change-Id: Ic264ca248d025fb5496fe0b48e8b3ec9376fb9e2
Merge "Specific /usr/local/bin/hus-cmd rootwrap filter"