Update converter to follow the new 1.1 specification

[mckn]

The following work has been done:

• Updated dependencies to newest version.
• Converter uppdated to support new 1.1 specification
• Converter can now handle deep objects as extras. They are flattened out and added as _fields.
• You can now also choose to use an dns name for the graylog host instead of a ip.
• Added so you can use layout-renderers in hostip and hostport. See example below:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="nlog" type="NLog.Config.ConfigSectionHandler, NLog"/>
  </configSections>
  <appSettings>
    <add key="graylogHostip" value="ip-here" />
    <add key="graylogHostport" value="port-here" />
  </appSettings>

  <nlog>
    <extensions>
      <add assembly="NLog.Extended" />
      <add assembly="Gelf4NLog.Target"/>
    </extensions>

      <target name="graylog"
              type="graylog"
              hostip="${appsetting:name=graylogHostip}"
              hostport="${appsetting:name=graylogHostport}" />
    </targets>

    <rules>
      <logger name="*" minlevel="Info" writeTo="graylog" />
    </rules>
  </nlog>

</configuration>

Best regards,
Marcus