Feature request: adjust the name based off of AWS_ENVIRONMENT

[DeviaVir]

I'm trying to automatically tie this function in with node-lambda, unfortunately they have some logic that automatically appends the AWS_ENVIRONMENT to the FunctionName: https://github.com/motdotla/node-lambda/blob/master/lib/main.js#L71

I didn't see a reason for not doing this with sqs-to-lambda as well, so I've added code that makes this possible. Hopefully it's useful for others as well.