Fix metadata editor

Convert slices to postgres arrays.

lib/database/books.go

@@ -4,6 +4,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/go-pg/pg"
+
 	log "github.com/cihub/seelog"
 )
 
@@ -132,7 +134,11 @@ func (db *pgDB) UpdateBook(id string, data map[string]interface{}) error {
 			setCondition += ", "
 		}
 		setCondition += col + " = ?"
-		params = append(params, val)
+		if col == "authors" || col == "tags" {
+			params = append(params, pg.Array(val))
+		} else {
+			params = append(params, val)
+		}
 	}
 	_, err := db.sql.Model(&Book{}).
 		Set(setCondition, params...).