Motivation:
migrate to the next major version of oncrpc4j-3.0.x. The highlights:

  - java9 ready
  - package name changes
  - update of external dependencies

Full changelog for oncrpc4j-2.7.0..oncrpc4j-3.0.1
    * [5f174e5] [maven-release-plugin] prepare for next development iteration
    * [09f1858] fixed stack overflow for recursive constant definitions
    * [d14a7df] Added input for service name while creating OncRpcClients. This makes it easy to identify threads created on behalf of a client.
    * [48a98be] src: make code base JDK9 ready
    * [64213d2] svc: explicitly specify which address to bind during tests
    * [2ffe42a] svc: use java8 stream to filer local end-point address
    * [d91499e] svc: add OncRpcSvc#toString()
    * [ca0539a] pom: update external libs and maven plugins
    * [b2d8247] src: more java8 clenups
    * [3e2dd59] Test case for issue #56 https://github.com/dCache/oncrpc4j/issues/56
    * [39f51cc] Bad maven module for issue test file
    * [6915c33] Add the missing owner parameter to mapping and rpcb operations
    * [b7b1691] Corrct an NPE when dumping an empty rpcbind registry
    * [b1ba74f] Add version properties for plugin/dependencies
    * [e452d65] Describe maven-jar-plugin in top level pom.xml
    * [f17cbd2] Remove unnecessary null check in generated code
    * [b185da2] pom: fix typo in plugin version property
    * [7aaca8e] utils: drop Bytes#to/fromHexString methods
    * [e0282c6] xdr: rename org.dcache.utils.Opaque into org.dcache.xdr.XdrOpaque
    * [68aa383] pom: bump project major number
    * [aac35af] src: split org.dcache.xdr into org.dcache.oncrpc4j.{xdr,net,rpc,util}
    * [766e70b] docs: update readme to describe new changes
    * [691ec88] pom: remove outdated java.net maven repos
    * [2680903] pom: update guava version to 24
    * [3c7f0bb] xdr: drop XdrBuffer
    * [7cb1fa0] xdr: introduce Xdr#getBytes method
    * [182521d] xdr: implement AutoCloseable interface
    * [fc41b2b] pom: add stable automatic module name into jar
    * [c30b87b] gss: use try-with-resource when Xdr is used
    * [b7eb9b6] rpc: rename GrizzlyXdrTransport to GrizzlyRpcTransport
    * [80c1b52] src: update copyright years
    * [b848ea0] libs: update to grizzly-2.4.3
    * [0ea08fe] [maven-release-plugin] prepare branch 3.0
    * [50f9543] [maven-release-plugin] prepare release oncrpc4j-3.0.0
    * [49bbec1] [maven-release-plugin] prepare for next development iteration
    * [24c87f2] xdr: do not flip byte buffer in Xdr#xdrEncodeByteBuffer
    * [085756e] [maven-release-plugin] prepare release oncrpc4j-3.0.1

Modification:
update pom file. Adjust to new package names:

org.dcache.xdr =>  org.dcache.oncrpc4j.rpc and org.dcache.oncrpc4j.xdr

Result:
up-to-date oncrpc4j

Acked-by: Paul Millar
Target: master