Merge pull request #6 from SpazioDati/master

Add parameters to the dataTXT service.
register NERChange to the RefineServlet to enable correct history load after restart
fix possible root of problems when reloading data from dump after restart
register NEROperation to allow correct "op" attribute in history-json
make NERServiceManager a singleton to allow service retrieval from everywhere in the code
implement the "reconstruct" method to allow for history-apply / reapply