Pulling in pgconf module from camptocamp/puppet-pgconf

This includes the following changes:
  - Hooking up pgconf module to postgresql to manage postgresql.conf
   - pgconf includes a type and provider for postgresql.conf the provider
     is a simple parsed file following basic ini parsing.
  - Add config_entry.pp which wraps the pgconf module.
  - Replace file_line resources by postgresql::config_entry in beforeservice.pp
  - Adding unit tests for the newly introduced functionality