Fix chef-update so that it launches the stack monitor
Only execpect s3 behavior when the s3 bucket argment has been passed
Only run the steps around the s3 upload when an s3 buccket has been passed in
Tweak bucket-name flag desc a bit to make it clear its required for an S3 upload
Merge pull request #52 from sportngin/chef-update-default

Switches the default chef-update command to only perform s3 uploads when neccessary