Rename c-pod::client recipe to c-pod::base

This recipe performs common setup tasks for both CentOS and Ubuntu
* Install avahi and nss-mdns and advertize SSH
* Setup apt and yum repos (yum.conf with multilibs=best)

Tidy up by removing unused recipes
Include c-pod::base where needed
Rename node[:cpod][:server_name] to :url

In line with CPOD_URL environment standard
Fix Docker and Socks recipes

Ubuntu installs latest Docker from repository
Socks configuration passes interface info correctly
Use the correct docker defaults

Tested on both CentOS and Ubuntu