/.well-known/web-keys uses wrong context

[msporny]

The current /.well-known/web-keys returns this:

{
  "@context": "http://purl.org/payswarm/v1",
  "publicKeyService": "https://dev.payswarm.com/i?form=register"
}

When it really should return this (note the change in @context):

{
  "@context": "http://purl.org/web-keys/v1",
  "publicKeyService": "https://dev.payswarm.com/i?form=register"
}