(from AES) Merge pull request #1497 from datawire/ark3/epc-kill-all-sessions
(from AES) Merge pull request #1497 from datawire/ark3/epc-kill-all-sessions

[Pen Test] Allow Log Out of All EPC Sessions

Adds a mechanism to invalidate all outstanding JWTs for the Edge Policy Console. The JWT's Subject field holds an optional nonce that must match the nonce stored in Redis.

- The original token from edgectl login does not have the nonce
  - This is accepted by the auth check
  - This token expires so we don't need to worry about it
- Any user activity refreshes the token, which adds the nonce
  - This is _the way_ we refresh tokens; there's no way to avoid this
  - The auth check requires this nonce to match the one in redis
- Clearing the nonce in redis causes a new one to be generated
  - The new nonce will be different (it's based on the clock)
  - So all old tokens will be invalid because the nonce won't match

Also adds a button in the Debugging page to log out of all sessions and an associated endpoint to clear/regenerate the nonce to achieve that.
datawire/ambassador,datawire/ambassador,datawire/ambassador,datawire/ambassador,datawire/ambassador