Don't export mail.jar/activation.jar from maqetta.core.server.

This should hopefully fix a build break caused by a "cycle"
between the plugins.
Merge branch 'master' of github.com:maqetta/maqetta

* 'master' of github.com:maqetta/maqetta:
  #3411 maybe it needs a bundle version
  #3411 remove debugger statement

Conflicts:
	maqetta.core.server/META-INF/MANIFEST.MF