Re-enable logging when running tests in maven build

[stephanr]

This is the “sledgehammer” method to provide a logger while running JUnit tests.
Needs to be discussed in a TMC meeting because of possible side efects.

pro

• does not require modification of every module

con

• does not work when running tests in IDE
• may interfere with modules which have a logger configured

Probably the only alternative in my opinion is to create a module like deegree-core-test with a src/main/ressources/simplelogger.properties and a compile-time dependency to org.slf4j:slf4j-simple which is manually added to each module (see #1606).

References

• Re-enable logging of SLF4J on tests to make automated test more useful #1587
• Identify packages with tests executed without logger implementation and add logger implementation #1606

closes #1587