STANBOL-811: The unit tests of the TopicEngine do no longer use temp files, but instead create SolrCores within the /target/enginetest-files and /target/trainingsettest-files folders - hopefully this fixes test issued related to missing index files on windows; In addition log4j is now used for logging during tests as this allows to set the log level for Lucene/Solr to WARN

git-svn-id: https://svn.apache.org/repos/asf/stanbol/trunk@1449609 13f79535-47bb-0310-9956-ffa450edef68