[push-api] Straw man for encryption (#130)

This builds on #129 by adding encryption based on https://tools.ietf.org/html/draft-thomson-webpush-encryption.  At the moment, this is just a strawman for discussion.
You can view, comment on, or merge this pull request online at:

  https://github.com/w3c/push-api/pull/130

-- Commit Summary --

  * Starting to remove subscription id
  * Tweak example
  * Removing subscriptionId
  * Missed a subscription id
  * Adding encryption stuff
  * Fixing grammar

-- File Changes --

    M index.html (150)

-- Patch Links --

https://github.com/w3c/push-api/pull/130.patch
https://github.com/w3c/push-api/pull/130.diff

---
Reply to this email directly or view it on GitHub:
https://github.com/w3c/push-api/pull/130