sender always return true for checkbox

[guidotripaldi]

It seems that the actual value for type checkbox input isn't reported correctly (on branch master), it always reports a true value when a checkbox is clicked:

# Template
<%= checkbox :permission, :read, value: true, drab: "change:test_checkbox()" %> Read
<%= checkbox :permission, :write, value: false, drab: "change:test_checkbox()" %> Write

# TestCommander
  defhandler test_checkbox(socket, sender) do
    IO.puts "test_checkbox, sender name: #{sender["name"]}, value: #{sender["value"]}"
  end