Duration Cannot Be >65,535

[alancheung]

First, love this library, it's amazing!

The documentation for LifxLan states that the duration is an unsigned 32-bit integer with a maximum value of 4,294,967,295 for regular turnOn commands.

It looks in lifx-lan-composer.js has several methods to calculate the maximum value for duration.

102:
  typeof(duration) !== 'number' || duration % 1 !== 0 || duration < 0 || duration > 65535
117:
  typeof(v) === 'number' && v % 1 === 0 && v >= 0 && v <= 0xffffffff
501:
  typeof(v) === 'number' && v % 1 === 0 && v >= 0 && v <= 0xffffffff
715:
  typeof(duration) !== 'number' || duration % 1 !== 0 || duration < 0 || duration > 65535
508
  typeof(duration) !== 'number' || duration % 1 !== 0 || duration < 0 || duration > Math.pow(2, 64)

The maximum values set in this library do not match LIFX support maximum values.

PR incoming as soon as I figure out how to pull :)