JModelica 2.4 Update

[dhblum]

This issue is to deal with unittests that fail from with JModelica 2.4:

• Small numeric differences in fmu simulation
• Deprecation warning for "extra_lib_dirs"

[thorade]

also see
https://stackoverflow.com/questions/49259284/adding-additional-libraries-to-modelicapath-in-jmodelica