Since https://github.com/saltstack-formulas/users-formula/pull/182 the
home directory was created by salt which prevent "adduser" behavior to
copy /etc/skel in newly created directory.

Ensure the parent directory of the home dir is existing instead.

Fixes #181

The state will not fail gracefully, instead you will get
an error like this one:

          ID: users_rhertzog_user_gitconfig_0
    Function: git.config_set
        Name: alias.br
      Result: False
     Comment: State 'git.config_set' was not found in SLS 'users'
              Reason: 'git' __virtual__ returned False
     Changes:

And since pillar data can't be (easily) tuned according to minion's
status, we really need this check here.

My tests with Salt 2017.7.3 have shown that cmd.has_exec() is reliable
for this, contrary the what the comment was implying.

* Add support for 'template' in 'user_files'

* Fix-up wrong nesting level for template value

* Small quality improvement for push upstream.

* Consistency improvement for variable name

This reverts commit 48416398e3.

Fixing my previous change which errors in a particular scenario.

Error: Conflicting ID 'users_ssh_auth_source_username_0' when keys are added and removed simultaneously.

Fixing the conflict and sending a new pull request

Fixes #118
Duplicate of #120

Fixes: 150

* add ability to configure prime_group without gid

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.