mirrorbits-del-stats: allow passing the host to redis-cli

[lazka]

Passing the host to redis-cli is only possible via the "-h" switch, which clashes with the "-h" interpreted as "--help" in the script.

Make "--" stop the argument parsing, so "-h" can be forwarded to redis-cli:

mirrorbits-del-stats daily:30 monthly:12 -- -h redis

[lazka]

@elboulangero

[elboulangero]

Looks good, thank you!

[lazka]

thanks!