Enable rate limiter by default

[ameshkov]

Just in case

[vbh689]

While we'are waiting for the solution. In case you want to enable rate limiting in "quick and dirty" way: 😈

sudo iptables --new-chain RATE-LIMIT
sudo iptables --append INPUT --match conntrack --ctstate NEW --jump RATE-LIMIT
sudo iptables --append RATE-LIMIT --match limit --limit 50/sec --limit-burst 20 --jump ACCEPT
sudo iptables --append RATE-LIMIT --jump DROP

[ameshkov]

We actually badly need it in v0.91 already -- to avoid additional setup steps for those who use their own VPS for AG Home.