Site cleanup notes

As part of cleanup:

• Add copyright and license text to all "distribution" files (anything downloaded by reader/client). Currently, the copyright for all of the existing content is (c) StrongLoop and IBM. The license for any code artifacts should be MIT.
• Remove comments for translation from YAML preamble in .md pages. We can add this back if required for any future translation iterations (Be careful not to remove the stuff in-between the comments!):

---
### TRANSLATION INSTRUCTIONS FOR THIS SECTION:
### TRANSLATE THE VALUE OF THE title ATTRIBUTE AND UPDATE THE VALUE OF THE lang ATTRIBUTE.
### DO NOT CHANGE ANY OTHER TEXT.
...
### END HEADER BLOCK - BEGIN GENERAL TRANSLATION
---

• On home page, replace text and link to http://loopback.io with link to new "Frameworks" page that lists LB as well as other Express-based frameworks.
• In the footer change, "The Express project is sponsored by StrongLoop" to say something like "Express is a project of the Node.js Foundation", and have it link to http://nodejs.org/foundation
• In header remove the "Express and Node.js training from StrongLoop" link.
• On translated pages, add "This translation provided by StrongLoop/IBM" or something similar. Also add to the home page where it links to the translations.
• Import changes from https://github.com/expressjs/express-api-docs/pull/3.

Home page banner commit: https://github.com/expressjs/expressjs.com/commit/daeac13b38ced6b354aa94f4ba6fb3c396981895