Refactor Query Expander to be more flexible

in number of topics per query element and top words per topic
Add id to TopicContainer

this is needed for query expander, because through sortation the id is no longer the line number
Add variation coefficient as output for TopicModelBuilder
Refactor MalletInputFileCreator to not use so much heap space anymore

also refactor DBManager to make the crawling faster
Fix ToDo so that QueryExpander transforms Query to lowercase
Don't wait for URLs anymore, just collect those which are already done.
Make Tweet Crawling faster by removing clean up parts every 1000 tweets
Implement a first example with OnlineLDA
Refactor MalletInputFileCreator

to be able to work with the input without writing it into a file,
but uses to much Heap Space in this case
Go on implementing online LDA

but not done yet
Implement crawler that collects all tweets from specified users