blackbox_exporter should validate config if version >= 0.13.0

[mapa3m]

Affected Puppet, Ruby, OS and module versions/distributions

• Puppet: 4.10.12
• Ruby: 2.0.0p648
• Distribution: CentOS 7.6
• Module version: 6.4.0

How to reproduce (e.g Puppet code you use)

class { 'prometheus::blackbox_exporter':
    version => '0.14.0',
    modules => {
      'http_2xx' => {
        'prober' => 'http',
        'foo' => 'bar',
        'http'   => {}
      }
    }
  }

What are you seeing

Config file is generated, copied over /etc/blackbox-exporter.yaml and, and blackbox_exporter dies on restart

What behaviour did you expect instead

Validation error

Output log

Any additional information you'd like to impart

Config validation functionality is available in blackbox_exporter version 0.13.0 and up.

[TheMeier]

@mapa3m care to provide a merge request for that?