Implements the part of publishing procedure related to pom.

This just add a parent from sonatype to javassist.

You will still have to follow the procedure of sonatype for the rest. Including addiding these lines to your settings file : 

```xml

<servers>
    <server>
      <id>sonatype-nexus-snapshots</id>
      <username>your-jira-id</username>
      <password>your-jira-pwd</password>
    </server>
    <server>
      <id>sonatype-nexus-staging</id>
      <username>your-jira-id</username>
      <password>your-jira-pwd</password>
    </server>
  </servers>
```

Issue https://github.com/icon-Systemhaus-GmbH/javassist-maven-plugin/issues/2