Add reclaim uber stamp

[dwik-reclaim]

Stamp Provider

• The Stamp provider name is globally unique (and should not have been used previously). This is because the provider name will be included in the record used to create the Stamp hash:
• The implementation has been unit tested
• Verification payload
  json
  valid: true / false,
  record: {
  ... // Unique payload identifying user
  }
• The attribute valid is false if the Stamp verification fails
• The record must contain the following attributes:
  • 1 or more attributes uniquely identifying the user:
    • An ETH address - it should always be lower case (not checksummed)
    • An email (in case of Google for example)
    • The users unique ID (like for Facebook, Twitter, Github)
• The payload should never contain a field named pii
  • This field is reserved for internal use