Add JAXB API dependency to coveralls-maven-plugin in java 9.
Add JAXB API dependency to coveralls-maven-plugin in java 9.

At least until [coveralls-maven-plugin issue 112](https://github.com/trautonen/coveralls-maven-plugin/issues/112) is fixed.

talsma-ict/umldoclet,talsma-ict/umldoclet