Show information about HNAP in index.html and info.html

The Pluto offers an info page on the Mass-Storage device and on its webserver. It shows basic information about the current versions of the various parts of the system (firmware, linux, u-boot, etc.), a short getting started and an update notifier.

Basically, it comes from `plutosdr-fw/buildroot/board/pluto/index.html` and is altered in various steps during compile time (information about the compiler is filled in) of the firmware and the start of the system (current settings are filled in).
Currently it is a static page, which checks for a new Pluto firmware image version using Javascript.
We could do a similar thing and check for a new HNAP firmware version.
Additionally, we could update the information on this page dynamically using javascript, so we can have a nice dashboard about the current state of the device.

We could put HNAP related information on this page:

- [x] HNAP logo
- [x] HNAP firmware version
- [ ] HNAP settings
- [x] HNAP firmware update notification
- [ ] HNAP statistics and current state of the device (connectivity, statistics), ...