Fix functionality of "sendToSignIn" property for "authOptions" as passed to "showBlockstackConnect" function

[markmhendrickson]

Regardless of the value I set for sendToSignIn (true or false) in the authOptions parameter, the introductory modal appears whenever triggering the showBlockstackConnect instead of going straight to the sign in popup.

import { showBlockstackConnect } from '@blockstack/connect';

var sendToSignIn = true;

let authOptions = {
  appDetails: {
    name: 'Humans',
    icon: `${window.location.origin}/favicon.ico`,
  },
  finished: ({ userSession }) => {
    window.location.reload();
  },
  redirectTo: '/',
  sendToSignIn: sendToSignIn ? true : false,
  userSession: userSession
};

showBlockstackConnect(authOptions);

See https://github.com/markmhx/humans/blob/master/app/services/session.js#L10 as triggered by https://github.com/markmhx/humans/blob/master/app/components/app-nav.js#L9