Update defaultserver to new py4j namespace

[belkassaby]

change net.sf.py4j. to org.py4j.*
*change dependency of defaultserver bundle from net.sf.py4j to org.py4j
*bump major version number

[belkassaby]

Hello @bartdag , here is a PR to update the defaultserver that is being used at Diamond Light Source. I'm working with Kichwa Coders to upgrade the py4j use at Diamond (they used the legacy version with net.sf.py4j namespace) to the new namespace org.py4j. However, the defaultserver in py4j-eclipse wasn't updated to work with the updated namespace.
Thanks!

[mwebber]

This change deletes the submodule in net.sf.py4j/py4j, but does not make any changes to the .gitmodules file. It's not clear what the intention is here.

• If the submodule is being removed, then also remove it from .gitmodules
• If it's not being removed, then consider updating the version in net.sf.py4j/py4j.

Either way, the commit message should mention what was done with the submodule.

Also, I see several files called org.jboss.ide.eclipse.as.core.prefs checked in; these probably don't need to be. If you do want them checked in, they should be in a separate commit, since they are unrelated (as far as I can see) to this change.