Add the ability to force polling when watching

[whatyoubendoing]

You can do this by supplying options to chokidar https://github.com/paulmillr/chokidar. Could be done similarly to waitchify - https://github.com/substack/watchify/blob/master/index.js#L27

[RyanZim]

Fixed in #14 and released as v2.6.0.