[WIP] Upgrade to JDK8 and latest stable Jackson release

[hahnml]

This PR is currently work in progress and will provide the following improvements:

• Update pom
  • Upgrade Jackson to latest stable release
    Requires additional effort since some of the methods used from version 2.2.0-rc1 became deprecated until the latest stable version 2.9.4.
    • Change serializeWithType(...) implementations to comply with Jackson 2.9.4 as follows:

      @Override
      public void serializeWithType(ChannelProxy value, JsonGenerator jgen, SerializerProvider provider,
              TypeSerializer typeSer)
          throws IOException, JsonGenerationException
      {
          WritableTypeId typeId = typeSer.typeId(value, JsonToken.START_OBJECT);
          typeSer.writeTypePrefix(jgen, typeId);
          serializeContents(value, jgen, provider);
          typeSer.writeTypeSuffix(jgen, typeId);
      }
      

    • Change call to ctxt.mappingException(...) in ContinuationDeserializer.java and ChannelProxyDeserializer.java to comply with Jackson 2.9.4 as follows:

      ctxt.handleUnexpectedToken([Class], jp);
      

    • Serialization of @id's seems to be different, changed serialized strings in JacksonSoupTest.java accordingly. This needs further inspection/tests, if the JACOB implementation still behaves as expected...
  • JDK 8
• Lookout for patterns in source as indicated in the CVE [ https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=jackson ].
• Test changes together with latest code from ODE master branch