core: Cygwin path conversion must replace slashes first
provisioners/shell: use detail level output for running
Ansible: Re-enable ControlPersist defaults when ANSIBLE_SSH_ARGS is used

Solve problem discussed in [GH-2952]
provisioners/ansible: add new option raw_ssh_args

Since the Ansible provisioner now potentially exports ANSIBLE_SSH_ARGS
variable, it is fair to allow to extend the content of this environment
variable (`ssh_args` parameters from ansible.cfg file have lower
priority)
Merge pull request #3088 from gildegoma/ansible-ssh-args

provisioner/ansible: Improve management of ANSIBLE_SSH_ARGS
synced_folders/rsync: convert to proper unix-style path [GH-3086]
Fix tests
core: Private boxes authenticate metadata box URLs too
providers/virtualbox: add post-comm customize step [GH-3080]
Update README
Clarify versionconflict error
Don't splat the bundler groups
More wording changes on version conflicts
v1.5.0
Update CHANGELOG
Up version for dev