[luci] how to transform multi input to one uci cfgvalue

[Michael Fung]

> Do you want two fields to act as one logical option or do you want to
> implement a whole new widget with custom html and stuff?
> 

Hi Jo,

I want two fields to act as one logical option.

Web form:
Hour: ___  Minute: ___

Correspond to one uci config option 'time', like:
    option 'time' '16:55'


Rgds,
Michael