Added two checkers for Puppet's DSL.

    Add two checkers for Puppet's DSL
    
    The first checker, `puppet-parser`, uses puppet's own `puppet parser
    validate` command to check syntax. The second checker,
    `puppet-puppet-lint`, is chained to the first and uses the
    `puppet-lint` program to check adherence to the Puppet style
    guidelines.
    
    Add four new unit tests to test single line and multiline error
    patterns from `puppet-parser`, and to test ERROR and WARNING error
    patterns from `puppet-puppet-lint`.
    
    Update the Vagrant provisioning script to install puppet.