make AdminIdentity configureable per user

See merge request !1

* 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.

Revert "User files state without defined home directory"

User files state without defined home directory

also load ssh keys from pillar data