tink hardware push returns no useful data

[alexellis]

tink hardware push returns no useful data - surely we can output something like "Inserted..OK", or some other data for users? The exit code can be checked, but is confusing.

tink hardware push "`cat /tmp/hardware.json`"
echo $?
0

Also can stdin be used to pipe the file or not?

cat /tmp/hardware.json | tink hardware push

This is unclear, but should be a workflow, putting the string in via args is not UNIX-like.

cc @gauravgahlot