VpsAdmin#install: fix node saving
VPS#features: use vzctl --netfilter instead of obsoleted --iptables
Version 1.21.2
Update changelog
Add shaper

Shaper rules created at init, add/remove/update operations.
Transactions for adding/removing shapers
Shaper: add global mutex, only one thread may manipulate it at a time
Firewall: use global mutex when registering IPs
Transaction for root shaper changing
Firewall/shaper init, flush and reinit via remote control
Remote control: add remote console using remote-pry
Shaper: support IPv6
Changelog for v1.22.0
Gemfile: fix pry-remote