added abbreviation extraction
** processing of abbreviations & save them to  mem-db
** searching of abbreviations in html description of the DictionaryEntries
- changed longForm to not unique in Abbreviations.scala data modell
- activated writing of abbreviations to db
changed Importer to an abstract class
* added importers for Georges and Pape data
** they implement the abbrv parsing method separately
finds abbreviation occurrences in entries, writes them to db
* added support for using abbreviations from another Importer
* code optimization
merged in importers * lifted unique constraint for longForm in Abbreviations