Fixed not throwing Exceptions

Seems that all of the places, the Exceptions were swallowed (always returned 200, which means everything went ok), now it's fixed all places where it was covered by the tests. Also the tests needed to be fixed, as they relied a null result instead of an Exception as the real DynamoDb would return an erroneous input.

Also added a new test suite and a little pom.xml config for it, now mvn test runs with both inprocess and server mode.