- added earliestPublicationDate for App/Models/Dataset.ts

- new classes TokenWorkerService.ts, TokenWorker.ts and ResumptionToken.ts for using REDIS with paging OAI results
- deletd public/asstes2/langCodeMap.xml: integrated it directly in datasetxml2oai-pmh.xslt
- added redis npm package
- added TokenWorkerProvider.ts for using singleton of TokenWorkerService inside OaiController.ts
- added config/oai.ts for oai related configs from .env-file
- adapted XmlModel.ts for grting domDocument from database

app/Library/Oai/TokenWorker.ts

@@ -0,0 +1,10 @@
+import ResumptionToken from './ResumptionToken';
+
+export default interface TokenWorkerContract {
+    ttl: number;
+    isConnected: boolean;
+    connect();
+    close();
+    get(key: string): Promise<ResumptionToken | null>;
+    set(token: ResumptionToken): Promise<string>;
+}