Implemented a special JUnit Runner to replace the Parameterized Runner
which is used for the database-related tests.

The KiWiDatabaseRunner works similar to a "normal" Parameterized Runner
but:
* expects a field of type KiWiConfiguration, annotated with @KiWiConfig,
  or:
* a constructor accepting exactly one parameter of type 
  KiWiConfiguration
  
Availability is checked directly by the runner, H2 is always tested.
(will be gradually used in the KiWi-Tests, such as MARMOTTA-285 and
MARMOTTA-287)