all: Port to Puppet

It's easier to deploy configuration files and packages using Puppet. Even
by using it, we still need to make sure it's installed in system.

One shortcoming of this tool is that, by trying to provide a high
abstraction of what commands the system should use in order to deploy
packages and files, it doesn't let a user step in and execute system
commands and retrieve their output. That's why I've needed to add some
extra lines to substitute "on-the-fly" the home directory in all the
manifest files.
setup_linux.sh: Install Puppet's module stdlib

This will be necessary to ensure that some lines are included in files.
commandline/manifests: Run Emacs in "no GUI" mode from terminal

When I run Emacs from the terminal, I prefer it to run in "no GUI" mode.
setup_linux.sh: Expand Puppet's module path rather than overwrite it

What `setup_linux.sh` was doing before is to overwrite the modulepath with
the `modules` directory. As a byproduct, any other module installed
previously, like "stdlib", wasn't being picked up.
Merge branch 'use-puppet'