Initial contributions from ShawnMilo.

Hi. Thanks for creating this! I was about to build it myself and then I found yours, which does more than I was planning on.

I made a few small changes. Mostly golint compliance, but also moved the environment variable reading to init() and also got rid of the constants that were duplication of the existing global vars.

I'm thinking, long term, into splitting out the API work you did into a separate package (perhaps "dnsme") instead of "main," so it can be used both by the cli tool and also other programs. That's actually what I want for my project.

Thanks,
Shawn