Support Chocolatey version 0.9.8.24+

Chocolatey moved things around in version 0.9.8.24

* Added only_if checks for upgrading chocolatey itself.
* Use the `ChocolateyInstall` Environment variable for the install
  location (thanks to feedback from issue #16). We no longer make
  assumptions about where Chocolatey is installed.
* Use powershell_script. This is only available in chef 11.6+
* Cleaned up rubocop errors
* Updated (and reflowed via `pandoc`) README

Closes #15
Merge pull request #16 from docwhat/cleanups

Support 0.9.8.24+ and Other Miscellaneous Cleanups
Refactor README
- add badges
- use same notation for level
Update tests to use Rake instead of deprecated strainer
adds options resource for custom command line args
Allow spaces in the path to the "choco" command.

The default directory where Chocolatey installs changed to
be "CommonApplicationData". On new versions of Windows this is
"C:\ProgramData", on older versions of Windows (XP, 2003) this is
"C:\Documents and Settings\All Users\Application Data".
Merge pull request #23 from 7digital/allow_spaces_in_chocolatey_path

Allow spaces in the path to the "choco" command.
Fix syntax error
Merge pull request #24 from 7digital/fix_syntax

Fix syntax error
Merge remote-tracking branch 'chocolatey/master'

Conflicts:
	attributes/default.rb
	providers/default.rb
	recipes/default.rb
	resources/default.rb