dropped unused dependencies on junit and slf4j, added dependencies for spray-caching and gwt-dev
removed annotation stub
this stub is now provided by the gwt-dev dependency
bufixes: lazy loading and initialisation issues for KeywordSearchService

* multiple initialisation of Spellchecker instances for the same language
* drastic reduction of time required to fetch all keywords from the DB to create the autocompleter
added file appender to root logger