Refactor to support both Exec backend in addition to Ssh
Anonymize ssh_exec method as do_check
Merge remote branch 'pr/34/head'
Bump up version
Fix README for multiple backends
Merge pull request #35 from raphink/dev/readme_multi_backends

Fix README for multiple backends
Move backends to a separate directory
Move OS helpers to a separate directory
Rename backend modules as Serverspec::Backend::*
Rename helper modules as Serverspec::Helper::*
Fix installed_by_gem edge effect
Use classes for backends

  Use an helper for backends again
  Instantiate backends with commands
  Remove specific implementations from matchers
Add Puppet backend
Merge remote-tracking branch 'pr/36/head'
Add obsoleted helpers to show warning message if obsoleted herlpers are included.
Merge remote-tracking branch 'pr/37/head'
Merge remote-tracking branch 'pr/38/head'
Remove dependency on Puppet from serverspec core. It should be optional.
More recognizable obsolete messages
Bump up version