Add support for ssh_auth_sources.absent

Fixes: 150

fix gitconfig url insteadOf example

Previous example would result in quote escaping problem

* add ability to configure prime_group without gid

temp fix on git executable

Add support for hash_password

fix wrong variable name in absent_users

set user and group of user dir in pillar

fix warning on managed file state for /etc/sudoers.d/username

fixing removing of users based on pillar['absent_users'], fix #126

Support for optional_groups

Fix typos in README.rst

Keep existing user's home and shell unless explicitly defined

Use `contents_pillar` to work with multi-line authorized_keys file

Properly handle dependencies on ssh_auth when home is not create with…

Create a system usergroup if user is a system user

If the user to be created is a system user, it makes no sense to create
him a primary group which is not a system group too.

Resolve `git.config` error where minion does not have Git installed #115

Default path for home folder in user_files.sls if home omitted in pillar [fixed style].

Pull changes from master

Pull changes from main repo.