Make PythonLibs truly an optional component

PythonLibs is an optional dependency, remove REQUIRED otherwise the
build fails when it is not found.
Merge pull request #96 from plfiorini/master

Make PythonLibs truly an optional component
Adding needed grub and initcpio to phase 2
New displaymanager module, based on Thus.
PEP8 displaymanager.
Create sddm.conf if it doesn't exist.
Let's assume for now that the ISO must ship a sddm.conf.
s/AutoUser/User/
Documentation.
Merge pull request #90 from calamares/displaymanager-module

New displaymanager module, based on Thus.