Enable h2 concurrent db access.

By setting AUTO_SERVER to TRUE multiple processes, e.g. the application itself and a SQL client like Squirrel SQL, can concurrently access the h2 database. More information: http://www.h2database.com/html/features.html#auto_mixed_mode
Removed uncommented and unused config.
Different inheritance strategies in cls hierarchy

By using different inheritance strategies per class hierarchy we gain flexibility when structuring the SHOGun2 database.
Remove unused import.
Merge pull request #22 from buehner/h2-concurrent-access

H2 concurrent database access
Merge pull request #24 from buehner/improve-inheritance-strategy

Different inheritance strategies in class hierarchy
Exclude model package from Cobertura coverage test
Fix cobertura exclude
Merge pull request #25 from buehner/cobertura-excludes

Exclude model package from Cobertura coverage test