message: Improve email-login component
diff: +{{#if login.isRunning}}
  + <div class="cardstack-email-loading">{{loadingMessage}}</div>
  +{{else}}
  {{#if cardstackSession.isAuthenticated}}
  - <p class='cardstack-already-authenticated-message'>You are logged in</p>
  + <p class='cardstack-already-authenticated-message'>{{loggedInMessage}}</p>
  {{else if cardstackSession.isPartiallyAuthenticated}}
  <p class='cardstack-partial-authentication-message'>{{cardstackSession.message}}</p>
  +
  + <button class='cardstack-restart-login-button' onclick={{action 'restartLogin'}}>{{restartLoginText}}</button>
  {{else}}
  {{input value=email type='email' placeholder="email@example.com"}}
  - <button onclick={{action login}}>Log in</button>
  + <button class='cardstack-login-button' onclick={{action login}}>{{loginText}}</button>
  + {{/if}}
  {{/if}}
  \ No newline at end of file
  