Document vault_password_file in intro_configuration

Fixes #9016

Also modifies the template action plugin to use this new param
when executing the file/copy modules for templating so that links
are preserved correctly.

Fixes #8998

Centos 6.x and below use an old RHT style of configuring hostname.
CentOS 7.x and better use systemd.  Instead of depending on the
distribution string which seems to have changed over the course of 6.x
we need to explicitly check the version.

Fixes #8997

Do not remove local role file if given on the commandline

attributes

Fixes #8594

Fixes #8998

Fixes #8983

Mention defaults subdirectory in a more visible way

Update playbooks_variables.rst

vsphere_guest module doc fix

All examples do not show it, so only someone reading the doc from
end to end would know about it.

using this (for testing purpose) :
  $ ansible-galaxy install COPYING
  - error: the file downloaded was not a tar.gz
  - COPYING was NOT installed successfully.
  - you can use --ignore-errors to skip failed roles.

this result in COPYING being erased, which is surprising for the user.
This also prevent erasing requirements.yml if someone use the wrong flag.

Fix a bug causing yum module to not update to latest in some cases

Fix the docs for glance_image.endpoint_type

very small and minor addition, but I couldn't find anywhere that answered this (now obvious) question I had of whether or not facts could also be yaml files.

zypper: handle lists of packages efficiently

Fixes #8806

Fixes #8925

Fixes #7284

Tracebacks are now catchable with ignore_errors and have streamlined output.  Also removes 'baby-JSON' for bash modules.

Fixes #8971

Add missing tag to roles file example.

Correct mysql integration indentation