WIP: Berksfile support
Rework CHEF berksfile support. If berksfile_dir is not used create temporary one.
Merge remote-tracking branch 'origin/master' into berksfile_support

Conflicts:
	littlechef/runner.py
Implement fixes requested by tobami.
Remove unnecessary if.
Add Berksfile documentation.
import tempfile for temporary directory creation.
Merge pull request #210 from haad/berksfile_support

WIP: Berksfile support