This change add the option --remote-sign for the patch-builder script
allowing the user to send the patch to a remote signing server, get the
it signed and download it signed.
Test plan:
PASS: Build patch without signing it remotely
PASS: Build patch signing it remotely
Story: 2010676
Task: 51341
Change-Id: I59631ea81f05133f47aa3036f6c9f29e1a02b9c2
Signed-off-by: Dostoievski Batista <dostoievski.albinobatista@windriver.com>