Add augeasproviders::instances class.  Fixes #78

* Add augeasproviders::instances class to allow ENC applications to define resources.
* Add module dependency for puppetlabs/stdlib.
* Add basic beaker-rspec testing.
* Add puppet-syntax and newer rspec-puppet for unit tests.
Add of pam type/provider with doc and unit tests
Use an augeasprovider type as base