Decouple state creation and storage, allow Led constructor access to state reference

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
Led isOn now determined solely by state.value. state.isRunning responsible for all interval based ops. Closes gh-351

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
Led.prototype.animate(opts)

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
v0.7.42

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>