Usage: index.js example.com input-file.txt
Given AWS credentials in the usual environment variables, and given an input file with lines that look like this:
foo.example.com foo-is-cname-for-this.example.com
baz.example.com baz-cname.example.com
qux.example.com qux-cname.example.com
Add CNAME records to AWS Route 53.
ISC.