Clarify why we add -q only for ssh

Python 3: the StringIO module is gone

Fixes 17 failing tests on Python 3.4, restoring the 8 failures we had
last Friday.

Output proper JSON from vbox dynamic inventory contrib script

fix no self pointer out of class.

Also get pipelining working for people who look to chroot as an example
for their own connection plugins

Note: In the latest v2 API, action handles become but chroot doesn't
reliably handle become.  Maybe we need to add a has_become attribute
that the action can display an appropriate error.

This can happen in chroot environments that don't have all of /proc
available

Helps connection plugin implementors understand how to structure
exec_command()

Fixes #12526

Update outdated comment

Since #12165 was merged, hostnames are properly validated.

We now use "sudo -n" instead of "sudo -k && sudo …"

Clarified that .yml, .yaml, and .json are allowable file extensions for inventory vars files

Also strip UnsafeProxy off of low level srings and objects to ensure
they don't cause issues later down the road

Fixes #12513

Typo in shell command in example

Python 3: make test_variable_manager_precedence pass

Fixes #12501

Due to the way we're now calculating delegate_to, if that value is based
on a loop variable ('item') we need to calculate all of the possible
delegated_to variables for that loop.

Fixes #12499

There doesn't appear to be anything that actually uses tmp_path in the
connection plugins so we don't need to pass that in to exec_command.
That change also means that we don't need to pass tmp_path around in
many places in the action plugins any more.  there may be more cleanup
that can be done there as well (the action plugin's public run() method
takes tmp as a keyword arg but that may not be necessary).

As a sideeffect of this patch, some potential problems with chmod and
the patch, assemble, copy, and template modules has been fixed (those
modules called _remote_chmod() with the wrong order for their
parameters.  Removing the tmp parameter fixed them.)

And update portions of code to expect the proper error.

Fixes #12512

It's not available on older versions of paramiko such as shipped in RHEL6

Fixes #12477