Show "More by" on author page

Uses Goodread's list of author's books, filtering out the books that are already in the user's library.

Requires the Goodreads dependency and API information.

cps/web.py

@@ -1134,7 +1134,7 @@ def author(book_id, page):
     name = db.session.query(db.Authors).filter(db.Authors.id == book_id).first().name
 
     author_info = None
-    other_books = None
+    other_books = []
     if goodreads_support and config.config_use_goodreads:
         gc = GoodreadsClient(config.config_goodreads_api_key, config.config_goodreads_api_secret)
         author_info = gc.find_author(author_name=name)