Bootstrap: Fetch github keys from http not https

Using https was failing.

Amend b857a3d
Ref #32
Install ruby package, don't install docs for gems.

Fixes #8
Create rails playbook

- Install gem package and install rails gem.
- Install rails globally as ansible default is user.

Fixes #10
Closes #39
Move postfix to webservers.
Add virtual_alias_maps to postfix playbook.
Move all from common to web folder.