Refactoring backend node service to support saving email address

- Moved from sponsorship-form to drc-backend
- Moved code around to have sponsorship.js and coming-soon.js
- Added mongodb client currently hardcoded to localhost
- Added a .save method for coming-soon to save an email address
- Reworked all ansible files to accomdate directory change
- part of #669
Adding validation/sanitization to backend
Adding mongodb connection URL to secrets files.
Adding UX for saving email address
Renaming file to match new scope.
Renaming collection name so its easier to work with in Mongo shell.
Merge pull request #673 from rackerlabs/gh-669

Refactoring backend node service to support saving email address