Move platform to only work with JDK's >= 11

* Several javax-prefixed packages are being removed from JDK (such as
javax.xml.bind) and one has to provide javax.packages via new
jakarta-bundles. See: http://openjdk.java.net/jeps/320#Java-EE-modules

Java 11 is LTS and we don't want to require anything beyond that at this
point. Next LTS will be 17 which will be the next target.

Classes are also now compiled for Java 11.

gitlab #486
gitlab #524

Change-Id: Ib2edf9401ada203412569fadef4f092344b1c553