Added feature to upload test results in to Refstack API signed with
your personal RSA key. Just do upload with key '-i PATH_TO_PRIVATE_KEY'.
You can use your general OpenSSH key ~/.ssh/id-rsa or
generate a new one with 'ssh-keygen -b 4096'.
Change-Id: Icce6d7146f0fa9de892d1f4785ef24f17fc9b286