Would be great to upgrade to Boto3

[dkarchmer]

I learned from this example when I first created an EB worker, but as I was pointing somebody else to it, I realized that now I am encouraging the use of older technology.
Using Boto3 would modernize the example

[CrawfishPress]

I'd second that, although being five-year old code, I'm not expecting any updates. :) I have been trying to find examples of elb-workers using flask, so far with no luck.