Fix writing of NFC URI records

We need to write the entire URL and not just the path which would
be empty in cases such as http://www.qt.io.

Change-Id: I3529e200088cc9192fa16626cb21fffcca7f26c5
Reviewed-by: Martin Leutelt <martin.leutelt@basyskom.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>
Neard: Read all availabe SmartPoster data

So far, Size, Action and MimeType were not read when detecting a
smartposter tag.

Change-Id: Ica283eac8248ef5ed73f8538eac76050b1310eef
Reviewed-by: Martin Leutelt <martin.leutelt@basyskom.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>
Improve some parts of the SmartPoster API docs

Change-Id: I09f087d84641447fcb5e9e906f3d665ed86102e3
Reviewed-by: Martin Leutelt <martin.leutelt@basyskom.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>