fix nodejs.package_version when no package is installed

`npm list` returns an empty dict when no packages is installed and `nodejs.package_version` was expecting a key from this empty dictionary.
Pass the local flag to abspath

This commit ensures that the call to abspath looks for the absolute path
of the local virtualenv instead of attempting to connect to a remote
host when local is True.
Added `checkinstall` support in nodejs.py#install_from_source()

If `checkinstall` is `True`, a distribution package will be built and
installed.
In Arch, supervisor config folder is supervisor.d
Arch bundles headers with base package

require/python.setuptools() doesn't need to raise when running arch linux.
Update system.py

ManjaroLinux support (arch based)
Merge pull request #238 from roblabla/patch-2

In Arch, supervisor config folder is supervisor.d
Merge pull request #243 from heyimmowee/patch-1

Add ManjaroLinux to the "arch" family
Merge pull request #239 from roblabla/patch-3

Fix Arch support in python module
Update version to 0.19.0-dev
Normalize Arch Linux distrib ID [#237]

Arch Linux changed their LSB distrib ID twice, so we have to the
three following IDs: "archlinux", "arch" and "Arch" (the current one).

We normalize the value so that distrib_id() always returns "Arch".
Merge pull request #241 from vaz-ar/master

Add Elementary OS (Ubuntu-based distro) to the "debian" family
Merge pull request #236 from amigrave/master

Added `checkinstall` support in nodejs.py#install_from_source()
Merge pull request #219 from apatry/patch-1

Fix KeyError in nodejs.package_version when no package is installed
Merge pull request #224 from troyjfarrell/virtualenv-local-fix

fabtools.python.virtualenv: pass the local flag to abspath