Merge remote-tracking branch 'identifier/master' into Develop

cps/epub_helper.py

@@ -77,6 +77,10 @@ def create_new_metadata_backup(book,  custom_columns, export_language, translate
     identifier2 = etree.SubElement(metadata, PURL + "identifier", id="uuid_id", nsmap=NSMAP)
     identifier2.set(OPF + "scheme", "uuid")
     identifier2.text = book.uuid
+    for i in book.identifiers:
+        identifier = etree.SubElement(metadata, PURL + "identifier", nsmap=NSMAP)
+        identifier.set(OPF + "scheme", i.format_type())
+        identifier.text = str(i.val)
     title = etree.SubElement(metadata, PURL + "title", nsmap=NSMAP)
     title.text = book.title
     for author in book.authors: