Support merging configuration from multiple files

[deric]

I've extended instructions for inheriting configuration from multiple files. It is required to modify inputs and outputs initialization. One way is to modify default params, or move this code to node's definition:

  class { '::telegraf':
    outputs  => hiera_hash('telegraf::outputs'),
    inputs => hiera_hash('telegraf::inputs'),
  }

Official Puppet modules shouldn't contain hiera_hash() calls, but default class parameter initialization doesn't work the same way in Puppet 3. I'll try to add some test for this feature.

[yankcrime]

Thanks @deric - this also addresses #27.