Translation bugs

[Sebastian1515]

• de/library/loans/: Translate Header of table
• de/library/loans/: Itemname by Author
• de/library/loans/: Dateformat
• de/library/loans/: Renew / Return button
• de/library/my-loans/: borrowed until
• de/library/my-loans/: (Un)returned loans
• de/library/my-loans/: "You have no unreturned loans."
• de/library/authors/: Page 1 of 18
• de/library/my-profile/: "Change password here"