Merge branch 'release/3.1.5'

oaipmh-core/pom.xml

.../java/info/textgrid/middleware/DublinCoreFieldLoader.java

...a/info/textgrid/middleware/IdentifierListDelivererDC.java

...nfo/textgrid/middleware/IdentifierListDelivererIDIOM.java

...info/textgrid/middleware/MetadataFormatListDeliverer.java

...re/src/main/java/info/textgrid/middleware/OAIPMHImpl.java

...c/main/java/info/textgrid/middleware/OAIPMHUtilities.java

...main/java/info/textgrid/middleware/RecordDelivererDC.java

...n/java/info/textgrid/middleware/RecordDelivererIDIOM.java

.../java/info/textgrid/middleware/RecordListDelivererDC.java

...va/info/textgrid/middleware/RecordListDelivererIDIOM.java

...e/src/main/java/info/textgrid/middleware/TGConstants.java

...re/src/test/java/info/textgrid/middleware/OaiPmhTest.java

oaipmh-webapp/pom.xml

pom.xml