[tei-council] small fixes to the oxygen-tei repo

Dear all, I had problems building the tei-oxygen plugin with Oracle Java 8. Alex (from oxygen) pointed me at a missing jar which I simply added to the lib folder within the tei-oxygen repo. Honestly, I have no idea of this java stuff and just did as I was told and it seems to work (on the Jenkins machines). It’s a little bit weired, since the missing class (BundleActivator) was never included in a JDK so the error should have popped up much earlier … Thought I’d mention this … Best Peter