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
Revert pull req #36, #37, #38
Merge branch 'revert'
Fix installed_by_gem edge effect
Bump up version
Revert version
Revert "Revert pull req #36, #37, #38"

This reverts commit 5df4e165214750f25776545389a3cccc0368f615.