Hardcode embedded glassfish version to 4.1
Hardcode embedded glassfish version to 4.1

This should for the maven-embedded-glassfish plugin to use version 4.1
instead of 3.X. Furthermore, the maven-embedded-glassfish plugin that we
have been using previously seems to have problems with 4.X thus I had to
upgrade it.

Fixes #5

stefanoberdoerfer/exmatrikulator,stefanoberdoerfer/exmatrikulator,stefanoberdoerfer/exmatrikulator,stefanoberdoerfer/exmatrikulator,stefanoberdoerfer/exmatrikulator