Fixes #3977

Supervisord can be installed at the user level or system level.
Installating as a user is particularly useful for systems without root access.

Adds the ability to provide a custom supervisorctl executable path, supporting custom installations

Fixed the example.

Adds more parameters which may be passed to supervisorctl:  config,
serverurl, username, password

Also refactored the various `module.run_command(build_a_string)` calls
into a single `run_supervisorctl` function.

  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

This updates the following modules to support check_mode:
* apt_key
* apt_repository
* easy_install
* pip - will always report changed due to the way it handles state
* seboolean
* selinux
* slurp - since nothing changes, it just adds that it supports
  check_mode
* subversion - reports changed when checking out new repo and
  when updating.
* supervisorctl
* svr4pkg

See issue #2114.

* Rename fail_on_rc_non_zero to check_rc, much more succinct.
* Simplify method defintion
* Fix command module and drop shell=shell option; whether to use
  shell is determined by if args is a list.

This updates apt, apt_repository, command, cron, easy_install, facter,
fireball, git, group, mount, ohai, pip, service, setup, subversion,
supervisorctl, svr4pkg, user, and yum to take advantage of run_command
in module_common.py.

 - added terse syntax to modules.rst
 - added description of special variables to template module

Added required as optional argument to get_bin_path(). It defaults to
false.  Updated following modules to use required=True when calling
get_bin_path():  apt_repository, easy_install, group, pip,
supervisorctl, and user.
Also removed _find_supervisorctl() from supervisorctl module and updated
_is_running() to not need it.