Cleanup database interface + other stuff

- Harmonize molgenis-app-omx molgenis_ui.xml with molgenis-app-lifelines molgenis_ui.xml
- Resolve some Findbugs issues
- Cleanup database interface, remove mostly stuff not working with JPA:
  - public Connection getConnection()  <-- always threw a UnsupportedOpExc
  - public void createTables() <--- not working with Hibernate4
  - public void updateTables() <--- not working with Hibernate4
  - public void dropTables() <--- not working with Hibernate4
  - public void loadExampleData(ExampleData exampleData) <-- use mock in tests instead
  - public <E extends Entity> List<E> findByExample(E example) <-- used getConnection
  - public List<Tuple> sql(String query, QueryRule... queryRules) <-- used getConnection
- Remove non-compiling generated tests classes that don't have a reference in Molgenis.java, rewrite in the future like other generated tests