plugin: redirects to "login" page (in metamask context)

[elmariachi111]

When event has been identified or uploaded and CID is known: redirect to the event-wallet app
with

?cid=cid&url=urlencode(current url)

• on mobile it should deeplink into the metamask browser if installed.
  maybe it's https://eips.ethereum.org/EIPS/eip-681 or https://eips.ethereum.org/EIPS/eip-681 maybe it's impossible.