release-ec2: trivial: help screen enhancements

Help screen enhanced to make parameters syntax clear

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
release-ec2: Introduce AWS regions list parameter

Parameter --override-regions added

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
release-ec2: Base released images on Linux AMI

Linux AMI suits OSv better because of default settings
instances inherit on creation - mainly preconfigured SSH
access and open SSH ports.

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
upload-ec2: Introduce script for images upload

Introduce script upload-ec2.sh that gets prebuilt
OSv images from S3 and converts them to EC2 AMIs.

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Merge branch 'ec2-release-scripts'