Enhance dbservices

Created by: NiklasRosenstein

This is a running PR that aims to make enhancements to the dbservices API.

Current changes:

• Support dbhost, dbport, dbname, schema parameter in DBService constructor, with appropriate fallbacks
• Raise RuntimeExceptions rather than log & continue (see #6 (closed), although in this specific case, I would like to raise a proper exception that can be handled gracefully in the Main class, coming soon^TM)
• Support these options when reading the configuration file, respectively (except dbport)