Added converter factory that is able to use path converter
added converter for converting classes into their names
Renamed ClassToStringConverter to match vaadin StringTo...Converter naming convention
added test for path converter
fixed missbehaviour of converter factory introduced due to wrong tests
added log4j.properties file for unit tests
fixed debugging information for intermediates
avoid returning useless converter paths (e.g. string to string)
prevent possible NPEs when null values given
added custom converter factory to ui