LevelDBTest JUnit-based integration test (incl. suitable POM)

[vorburger]

No description provided.

[vorburger]

@chirino can I do anything here (clean up?) to get you to merge this? Tx!

[chirino]

I don't fully get this change. Unit test exist in:

https://github.com/fusesource/leveldbjni/blob/master/leveldbjni/src/test/java/org/fusesource/leveldbjni/test/DBTest.java

And each platform build should be running those unit tests already.

[vorburger]

@chirino Duh! I admit I .. simply hadn't noticed DBTest, sorry. Noted it now, understood how surefire is configured to ignore it in that project by default, and how the platform builds use <testSourceDirectory>${basedir}/../leveldbjni/src/test/java to run it...

Also figured that an mvn -Dtest=DBTest test run in that project allows to run it, which will come in handy to test #90 (that was my main reason for doing it).

Abandoned this!