Merge pull request #12 from dennishendriksen/master

Move persistence.xml, index PalgaSample
Added retrievalterm importer
Made fields nillable
Lookuplists and hide annotators
Thesaurus and retrievalterm importers
Removed commented code
Optimalizations
Elasticsearch config file for palga
Merge pull request #13 from erwinwinder/master

Palga importer
Fix mref searching
Merge pull request #14 from erwinwinder/master

Fix mref searching
improve importer performance: flush/clear cache