Introduce AbstractExtDirectService

The AbstractExtDirectService extends the AbstractCrudService and provides additional methods, which can be used to load/modify stores or load forms in a EXT client. All currently available services have been adapted to extend the new service.
Adapt Model annotation of all models.

Adapted the crud-methods, which are configured in the Model-annotations.
Adapt the webapp-archetype to the new services.
Merge pull request #31 from buehner/ext-direct-service

Introduce AbstractExtDirectCrudService
Add PagingResult class.

This class is used to return the result of a paging request. It contains a result list and the total number of persisted rows.
Add a method for paging requests to the genericDao
Add a read method with sort and paging support.

This method will most likely be called by the ext direct proxies from the client. It currently supports sorting (with multiple sorters) and paging. It should be extended by filtering features in future.
Adapt readMethod in models.
Adapt readMethod in webapp-archetype.
[Refactoring] Renamed method.
Add PagingResult to excludes of coveralls.
Add hamcrest dependency for service tests.
Refactor and extend the tests of Abstract services.

Testing the AbstractExtDirectCrudService (which inherently makes use of the AbstractCrudService) now. Added missing tests.
Remove System.out.println
Merge pull request #32 from buehner/ext-direct-paging-sorting

Add ext direct support for remote sort and paging.
Update doc submodule.