Rename author to authors and subject to tags

lib/database/books.go

@@ -5,15 +5,14 @@ import (
 	"time"
 )
 
-// TODO: Author -> Authors, Subject -> Tags
 type Book struct {
 	Id          string
 	Title       string
-	Author      []string `sql:"authors" pg:",array"`
+	Authors     []string `sql:"authors" pg:",array"`
 	Contributor string
 	Publisher   string
 	Description string
-	Subject     []string `sql:"tags" pg:",array"`
+	Tags        []string `sql:"tags" pg:",array"`
 	Date        string
 	Lang        string
 	Isbn        string