A few things going on here:
 - move into the new {{id}} strategy where we use hostname
 - merge parts of the initial digitalocean migration pr
 - split variables meant for change into jenkins.conf
 - simplify all the things

refs: nodejs#242

 - start the transition to global variables (open up for roles)
 - include variable files by default
 - avoid variables in names since they can't be expanded
 - use jinja2 templating instead of replacing variables
 - change subshelling in init script
 - make init script slightly more robust