add a function for the backend to expose vid/pid of an opened device
add yk_get_key_vid_pid() to get the vid and pid of an opened device
let ykinfo print vid/pid
fixup libusb vid/pid function
preparing NEWS for 1.16.0
look at usagePage and usage to make sure we get a keyboard interface
NEWS
Typo.
release 1.16.0
bump versions
don't overwrite the error in ykp_import_config()

fixes #50
clarify that import is only available for the json format

relates #50