ENH: Add root user check in xt_recent, and add missing actionstop

Thanks to Helmut Grohne on IRC for suggestion
BF: $EUID not avilable in all shells, replaced with `id -u` in xt_recent
Merge pull request #618 from kwirk/xt_recent-tweaks

ENH: Add root user check in xt_recent, and add missing actionstop