Check usability of nfs on host
Remove check for nfs in config
provisioners/ansible: minor change in unit tests
provisioners/ansible: show ansible-playbook in use

Motivation:
By printing out the ansible command used behind the scene, we can ease
the support effort to very quickly identify whether a problem is due to
Vagrant provisioner or Ansible itself.
fix typo

link -> like
Merge pull request #3630 from also/patch-1

website/docs: fix typo
Merge pull request #3628 from gildegoma/ansible-show-cmd

provisioners/ansible: show ansible-playbook in use
Update CHANGELOG.md
providers/hyperv: vagrant ssh_run action [GH-3615]
Merge pull request #3625 from sciurus/check_nfs_usability

synced_folders/nfs: implement usable?
Update CHANGELOG
commands/init: minimal flag [GH-3611]
website/docs: update init command
guests/linux: LANG=en for ifconfig [GH-3029]
guests/debian: setting hostname works without 127.0.1.1 [GH-3271]
Update CHANGELOG.md
provisioners/ansible: try to improve unit tests

I still cannot explain the cause of these random errors in this unit test,
but it is anyway safe and suitable to update the test code as following:
- use stricter regular expression matching (-l is included in --limit)
- array lengths substraction instead of array contents substraction
Merge pull request #3632 from gildegoma/ansible-random-errors

provisioners/ansible: try to improve unit tests
guests/debian: fix tests
guests/debian: more tests for hostname