Update pom.xml
Update pom.xml

This patch fixes pom.xml issues only,
and does not update any dependency versions, etc.

- Add implicit dependencies
-- MetricsObjectSerializer
    depend on com.fasterxml.jackson.databind.ObjectMapper
-- REST related tests
    depend on org.json.JSONObject
   Note: SdnIp.java uses import net.sf.json.JSONObject

- Mark restlet related runtime dependencies as runtime

- Change declared netty dependency
  Note: This patch is not actually updating netty version,
  we were already using this version as side-effect of other
  dependency.

Change-Id: I398919e77154e50a61979048aedbeb2424275040

opennetworkinglab/spring-open,opennetworkinglab/spring-open,opennetworkinglab/spring-open,opennetworkinglab/spring-open,opennetworkinglab/spring-open,opennetworkinglab/spring-open