OO-3106: exclude large doc per default, fail fats if the index directory doesn't exists, remove print out

OO-3102: make to print view of test statistics works with the test resource and not only within a course

OO-3087: cancel the search if timeouted, make the timeout configurable, reduce it to 15 seconds, implement it for spell checker too

OO-3087: add a timeout to the full text search requests, free the DB connection before doing the search

OO-3076: use the max. number of uploadeable documents from submission settings as default in the revision process