Adding APP_DATA_PATH entry to the default app.ini.

conf/app.ini

@@ -93,6 +93,8 @@ KEY_FILE = custom/https/key.pem
 ; Upper level of template and static file path
 ; default is the path where Gogs is executed
 STATIC_ROOT_PATH =
+; Default path for App data
+APP_DATA_PATH = data
 ; Application level GZIP support
 ENABLE_GZIP = false
 ; Landing page for non-logged users, can be "home" or "explore"