feat(semantic-release): implement for this formula

* Based on `ssf-formula` (v0.3.0)
  - https://github.com/myii/ssf-formula/pull/5
* Unable to use `pillar.example` directly for testing
  - Used it as a basis for `test/salt/pillar/default.sls`
  - Brought useful changes back to `pillar.example`
* Fix: avoid `users/googleauth.sls` for `RedHat` & `Suse`
* Close #203

fix(init): replace `gid_from_name` (deprecated in `develop`)

added dir_mode logic for users.user_files

* Close #198
* All details in that issue
* Solution based upon:
  - https://github.com/saltstack-formulas/vault-formula/pull/35#issuecomment-509854411

This fixes a change introduced by 634deac where createhome was changed from True to False (by default).

This change honnor the default "global default" "users.createhome" from defaults.sls

fix(macos): ensure correct prime_group value

make AdminIdentity configureable per user

Groups members

add example of groups init into pillar.example

using `|json` would let the state get an error if gid is a string, as it would
not be converted.

Using directly the `None` yaml value, and letting numbers as string be
converted by yaml parser.

members, addusers, delusers, and in pillar examples

Also remove warning for passing unknown arguments on group.absent

added OpenBSD data

reworked "createhome" (variable, passwd entry & issue #164)

wrong author on local

support password expiration

[users/init] use dir_mode in addition to mode

To get it to work with RHEL7 with salt 2018.x

Allow state to update the gid

Improvements for ssh known hosts handling

Add possibility to remove user's git config keys

The former is deprecated since Carbon.

fix iteritems

added feature to create groups and set their gid

add import defaults.yaml

Dont require vim-formula by default

Fix default behavior of copying /etc/skel when creating home directory