- added doi registration

- npm updates for webpack-encore and postcss-loader
- DatasetExtension.ts: use relation contributors for PersonContributor
- added DoiClient.ts and DoiClientContract.ts
- rozes.ts: addes routes for creating and storing doi identifier
- addes xslt doi_datacite.xslt needed for registering DOI identifier

app/Exceptions/DoiClientException.ts

@@ -0,0 +1,12 @@
+class DoiClientException extends Error {
+    public status: number;
+    public message: string;
+
+    constructor(status: number, message: string) {
+        super(message);
+        this.status = status;
+        this.message = message;
+    }
+}
+
+export default DoiClientException;