fix a bug introduced by aws cli change of CreateSnapshot Response #247

[mingliangfeng]

See boto/botocore#247.

Tags key was removed from CreateSnapshot response, which means one column is removed from the result of "aws ec2 create-snapshot". To get the right snapshot id, need to use "cut -f 4"; "cut -f 5" is getting the timestamp, not snapshot id.

[colinbjohnson]

@mingliangfeng - thank you for the PR - looks like it can't be merged, but I've taken your advice into consideration - I've modified the code to use aws ec2 create-snapshot --region $region --description $ec2_snapshot_description --volume-id $ebs_selected --output text --query SnapshotId - where --query will allow me to select the return value of a given command - in this case, I only get SnapshotId back, so I don't need to use cut at all.

[mingliangfeng]

Good to see it is fixed.