user page remote follow form bug fix, add protocol field

thanks for reporting @tantek!

templates/user.html

@@ -59,6 +59,7 @@
         placeholder="@user@domain.social" alt="fediverse address"
         value="{{ follow_url or '' }}"></input>
  <input name="domain" type="hidden" value="{{ id }}"></input>
+ <input name="protocol" type="hidden" value="{{ g.user.LABEL }}"></input>
  <button type="submit" class="btn btn-default">Follow</button>
 </p>
 </form>