Added a check to the test

* Made TestMessage class static for gson. (stupid me).

Faking the date for compare test.
not using string check anymore

not relaying on the date anymore
using de and serialistation at one now.
removed obsolete comment
added a couple more tests
Merge pull request #75 from jan-schreib/dropserializertest

Added more checks for the drop de and serializer
added log4j2 configurationfile
Merge pull request #79 from hartmannaf/log4jconfig

added log4j2 configurationfile
update class diagram
Improved DropListenerTest
The test now checks if the expected number of DropListeners is called
and if DropListeners for other ModelObjects remain uncalled
Merge pull request #86 from L-Henke/ImprovedDropListenerTest

Improved DropListenerTest
Merge pull request #84 from k-c13/uml-class-diagram

update class diagram