Display ui time with customize time location (#7792)

* display ui time with customize time location

* fix lint

* rename UILocation to DefaultUILocation

* move time related functions to modules/timeutil

* fix tests

* fix tests

* fix build

* fix swagger

custom/conf/app.ini.sample

@@ -547,6 +547,9 @@ MAX_FILES = 5
 ; Special supported values are ANSIC, UnixDate, RubyDate, RFC822, RFC822Z, RFC850, RFC1123, RFC1123Z, RFC3339, RFC3339Nano, Kitchen, Stamp, StampMilli, StampMicro and StampNano
 ; For more information about the format see http://golang.org/pkg/time/#pkg-constants
 FORMAT =
+; Location the UI time display i.e. Asia/Shanghai
+; Empty means server's location setting
+DEFAULT_UI_LOCATION =
 
 [log]
 ROOT_PATH =