NFC tag support

[mofosyne]

Well might as well support NFC tags for specific media types. E.g. html page.

I have already tested if smartphone can read html encoded NFC tags by default. Answer is no. Also plain text cannot be read too.

Basically if you want to read any "mime type" encoded ndef record, you need a corresponding NFC tag intentfilter.

So we should at least adopt both text/plain and text/html and any other possible media people would want to encode in NFC tags.

---

Classified as not very urgent, since 1kb tags is typical. Tho you can get 8kb tags, but they are not cheap. I do expect NFC tags to get cheaper over time however. And support for NFC enable android watches should be done to read these NFC tags (especially since these watches don't have cameras to scan QR codes)