Move to Sonatype

[stonier]

A final move to sonatype would be the ideal place for a ros maven repository. Benefits:

• Long term it forces us to sync with mavencentral.(the ultimate repository of all things java)
• We can scale (this git repo will quickly becoming too big)
• People can manage their own uploads and contributions
  • No human intensive bottleneck at the pull request stage here.

For now though this would be a big job. Areas that need to be worked on:

• Upgrade the gradle logic for signed, automated publication to sonatype.
  • Official Guide
• Our rosjava 3rd party dependencies need to become mavencentral dependencies
  • we have quite a few custom artifacts in here
  • lots of testing!
  • Perhaps recreate some artifacts ourselves and push that to sonatype.