Add explicit public domain language and files

[virtix]

@see http://creativecommons.org/publicdomain/zero/1.0/ as well as CFPB/Qu

[dlapiduz]

It looks good! 👍

[cmc333333]

There are a several libraries that are not public domain in this repo:
https://github.com/cfpb/ec2mapper/tree/master/node_modules
https://github.com/cfpb/ec2mapper/tree/master/public/js/lib
https://github.com/cfpb/ec2mapper/blob/master/public/stylesheets/bootstrap.css
https://github.com/cfpb/ec2mapper/blob/master/public/stylesheets/bootstrap-responsive.css
https://github.com/cfpb/ec2mapper/blob/master/cron.js
https://github.com/cfpb/ec2mapper/blob/master/date.js

We need to make exceptions for those (and, I think, replace date.js)

[virtix]

/cc @cjfont who should review

[cjfont]

The correct way to publish node.js project with dependencies (and the way I should have done it in the first place) is to not include the modules as part of the project, but rather update the package.json file with the dependencies and their versions. This way only our own code is hosted and during installation the user simply runs "npm update" to download dependencies from the npm repository. I think date.js and cron.js are not in npm and will need to be handled separately -- I will look at those.