Merge pull request #24 from dongpf/master

fix TestTopicalWordCountWithStopWords.test() failure bug.
Forgot to re-trash OUTPUT of TestSolrOutputFormat
Changed default instances folder to user-located folder ./pangool-instances as of #25 + Properly remove all instances generated by unit tests.
Updated change log.
Merge pull request #2 from datasalt/master

merge pull from datasalt/pangool master