Feature: ability to set custom sudo command

sometimes it's more comfortable (because of suduers settings) to use
sudo -u user cmd

sometimes it's better to have
sudo su user -c 'cmd'
sudo su - user -c 'cmd'

or even
echo 'cmd' | sudo su - username

it's good to have possibility to change the default wrapper.

At this moment I have a server farm with lot of servers and it looks easier to adjust capistrano script than sudoers on all the servers.

And it's also good to have 'default' sudo user for capistrano. So by deafult it creates files / directories using the same user as was used for ssh connection. But for my case i login using my own account, but do a deploy using account common for all users (and which are not possible to connect via ssh).