Remove check of hardcoded AWS region list.

Add CoreOS facts detection, fix https://github.com/ansible/ansible-modul...

made certain flags part of base to make them universally settable

Fixed a few typos in the become documentation

Make some of the optional requirements optional for testing -- we'll skip the tests instead

You can extend boto to point at other regions that are defined in a
private cloud by defining ``BOTO_ENDPOINTS`` or ``endpoints_path`` in
the ``~/.boto`` file.

Ansible was doing a premature check against a hard-coded list of regions
that interrupted this possibility.  This commit removes that and
clarifies what the user can do if they specify a non-AWS region.

Prefer dnf to yum.

On Fedora 22 and later, yum is deprecated and dnf is installed by
default. However, the detection do not seems to take this in account,
and always use yum, even when yum cli is just a wrapper to tell "use
dnf", as this is the case on F22 and later ( see package dnf-yum ).

As dnf is not installed by default, except on F22, this shouldn't
break anything.

Vagrant inventory: exit 0 on success

Use abc for BaseCacheModule

Remove old dead code ( variable no longer exist, not used )

Fix errors reporting for playbook/*

Do add a unused named argument using a variable that was removed

Fix serialize function by using the right members name

Fix variable name

problem that the update fixes:

https://github.com/ansible/ansible-modules-core/issues/1064

Found by pylint.

There is no 'role' variable, and given the test and code after, that's
likely a test on 'ds'

Fix the filename in error message (pylint)