Remove package test
Unit test stub for AbstractService
Test suite that runs all scalatest tests
Move test for serializer to respective util package

Add SerializerTest to TestAll
Test: create test assets
Model: avoid NullPointerException in compare()
Assets: fill database correctly
AbstractServiceTest: use assets in before and after
AbstractService: prepare for JPA use
Assets: small improvements

- createAbstract() method
- test data that covers more cases
AbstractService: implement methods and tests
Fix bugs that produced compile errors

- Fix removal of authors, affiliations and references on update and delete
- Add equals method to Model
Merge pull request #28 from stoewer/master

AbstractService: implementation of all methods and tests