Improving offline mode

[jajberni]

I've been trying to improve the IotWebConf16OffLineMode example by preventing the node from going offline if the user is connected to the AP. This should be possible by reading the ApConnectionState _apConnectionState state variable https://github.com/prampec/IotWebConf/blob/7128981059ba55d84c480e8cf66c03e10276e1fa/src/IotWebConf.h#L599.

Unfortunately, there is no public function exposing this state.

It would be great to add to the IotWebConf.h something like this:

ApConnectionState getApConnectionState () { return this->_apConnectionState; };