v1.0.6

1. Replaced gulp with webpack.
2. Fixed missing entry point in package.json (#108 and #109)
3. Deprecated workerTrain(set, callback, options) in favor of trainAsync(set, options) : Promise.
   • 3.1 workerTrain will keep working for backwards compatibility reasons, but it will log a warning.
   • 3.2 Added schedule support to trainAsync, now it has the exact same signature as train, it supports the same options and returns a Promise of the same training results that train would return { error, iterations, time }