Support for Vaadin 7.5

[rpiaggio]

When attempting to use Vaadin 7.5 I found out that since version 7.4 the interface com.vaadin.server.DeploymentConfiguration declares some methods not present in org.vaadin.playintegration.PlayDeploymentConfiguration.

I made it work by adding to the latter:

  override def getWidgetset(defaultValue: String): String = conf.getString("widgetset").getOrElse(defaultValue)

  override def getClassLoaderName(): String = conf.getString("classloader").orNull

  override def getResourcesPath(): String = conf.getString("resources_path").orNull

  override def getUIClassName(): String = conf.getString("ui_class_name").orNull

  override def getUIProviderClassName(): String = conf.getString("ui_provider_class_name").orNull

  override def isSendUrlsAsParameters(): Boolean = conf.getBoolean("send_urls_as_parameters").getOrElse(true)

  override def isSyncIdCheckEnabled(): Boolean = conf.getBoolean("sync_id_check_enabled").getOrElse(true)