timeit shows a speedup of ~3x on Python 2.7.5 x86_64.
It also makes the code a bit shorter.

Fixes #4088

Users who use the command module for pretty much all shell commands may be stymied when they try using a command with <, >, $VAR, etc., and not know that they can use the `shell` module instead. This documentation fix clarifies this.

Revert "No longer need to reference 'version_added' in docs for these, as this was quite a while ago."

This reverts commit ff0a41d4.

raise errors when omitted, updated changelog with new modules.

relative pathing comes in handy on occasion, particularly when
delegating to localhost and running some command out of your playbook
repo. Making use of os.path.abspath will allow for the full path to
chdir and executable to be discovered if not provided.

  Migrated all examples: in DOCUMENTATION=''' string to standalone EXAMPLES=''' string
  Added deprecation warning to moduledev.rst and remove deprecated example from it
  Fixed up a few typos and uppercased some acronyms.
  add consistency to how EXAMPLES are formatted