Added annotations for adding user documentation that is shown if EvoAl is called without any parameters. #10

Implementing #3. The conversion is successfully tested. A practical test with reading the Arff directly in the training is still missing.

#7 Created interfaces from existing PropertiesReader and PropertiesWriter. Moved the JSON-based implementation to the main package since they are not part of the actual API. The reader and writer can be instanciated useing the PropertiesIOFactory which chooses an implementation based on the file ending.