Add HTML page to send WoL signals

This adds an embeddable HTML page to send WoL signals. I figured others might find it useful as well :)

I hope the change in core/vfs/config.in is correct. Many variables in there seem to declare the same dependency twice, like this
```
dep_bool "Inline ADC" ADC_INLINE_SUPPORT $ADC_SUPPORT $VFS_INLINE_SUPPORT $ADC_SUPPORT
```
Now I am not sure whether I misunderstood the syntax (I assume everything starting with $ is a dependency, i.e., it must be enabled for this option to be available) or whether the two `$ADC_SUPPORT` are unnecessary duplication.