Fix dataset type determination

The code for deciding on the dataset type was poorly transfered by me.
In the RLP harvester a dataset is only a document, if and only if all
its resources are PDFs. That is now correctly reflected in the code.

Signed-off-by: Konrad Reiche <konrad.reiche@fokus.fraunhofer.de>
Make translator configuration file path sensitive

I forgot to make the configuration parsing in the translator module path
sensitive as well. Before the translator code for mapping the groups
could not find the configuration file.

Signed-off-by: Konrad Reiche <konrad.reiche@fokus.fraunhofer.de>
Add unit test for Berlin CKAN Harvester

I have created a new directory for unit tests. In the README file I have
appended a section describing a way to execute unit tests in the future.
To improve the testability I have refactored the code from the import
stage into using another method which is only responsible for ammending
the package.

Also with this commit I have moved the logger format code into the
configuration file.

Signed-off-by: Konrad Reiche <konrad.reiche@fokus.fraunhofer.de>