Support for hocon format

[bugthesystem]

implements #230

Sample HOCON

# Test HOCON
app {
  name = My App  #comment
}

Sample code

trait ApplicationConfig {
  def name: String
}

val repository = "https://github.com/username/config-repo.git"
val branch: String = "staging"

val provider = new ConfigurationProviderBuilder()
      .withConfigurationSource(
        new GitConfigurationSourceBuilder()
          .withRepositoryURI(repository)
          .withPropertiesProviderSelector(new HoconPropertiesProviderSelector())
          .withConfigFilesProvider(new HoconConfigFilesProvider)
          .build())
      .withEnvironment(new ImmutableEnvironment(branch))
      .withReloadStrategy(new PeriodicalReloadStrategy(5, TimeUnit.SECONDS))
      .build()

val config = provider.bind("app", classOf[ApplicationConfig])

println(s"App name=${config.name}")