Add scp support

Transfer support of paths via scp.

Usage: scp "ssh-target" localpath remotepath arguments
For example you want to transfer from the shell "host" to target.
You want to tranfer /tmp/myMOTD to /etc/MOTD
shell "host"
scp target /tmp/myMOTD /etc/MOTD

Change-Id: I2c6ea978aab84ea921469e8c20541db9ea2925c6
Signed-off-by: Stefan Nygren <stefan.nygren@hiq.se>