Fix deploying to aws v4 regions

[andreialecu]

This changes the deployment code to use a different package that can support v4 signatures, which are required for newer AWS regions.

See #19

[nikDemyankov]

Thanks! Will test it.

[nikDemyankov]

Merged, thanks!

[nikDemyankov]

@andreialecu
After moving to s3-sync-aws package when I try to install CLI client - I get the following warning:

npm WARN EPEERINVALID [email protected] requires a peer of level@~1.3.0 but none was installed.

Warning can be removed by manually running npm install level. Some problem with dependencies in package.json in s3-sync-aws.