libs/core: Add Pythonic string formatting syntax
libs/core: Add Pythonic string formatting syntax

deepak78/luci,8devices/luci,8devices/luci,deepak78/luci,8devices/luci,deepak78/luci,deepak78/luci,8devices/luci,deepak78/luci,8devices/luci,deepak78/luci,deepak78/luci,8devices/luci,deepak78/luci