Run integration test on compiled Rascal jar

[rodinaarssen]

Is your feature request related to a problem? Please describe.
After compilating the Rascal project, the fresh Rascal jar is not tested. #2088 would have been caught, had we tried to run anything.

Describe the solution you'd like
At the very least, run some basic tests (cf. rascal-maven-plugin) in the verify phase of Maven, putting the fresh Rascal jar on the classpath.