message: change handler to blockstack
diff: @@ -4,7 +4,7 @@ import queryString from 'query-string'
  import { decodeToken } from 'jsontokens'
  import { makeAuthRequest, verifyAuthResponse } from './authMessages'
  -const BLOCKSTACK_HANDLER = "web+blockstack"
  +const BLOCKSTACK_HANDLER = "blockstack"
  const BLOCKSTACK_STORAGE_LABEL = "blockstack"
  const DEFAULT_BLOCKSTACK_HOST = "https://blockstack.org/auth"
  