Known breaking changes:
 * Usage of `Buffer.from` instead of constructor.
 * Usage of `Object.assign`.
 * Usage of "through2" & "concat-stream" instead of "event-stream".
 * Errors are now passed to the stream explicitly.

Test suite:
 * Both gulp buffer & stream modes are used.
 * Some arrow functions are used for readability.

Most users should not be affected by these changes. The exception
is when old node versions are used (before v4.0.0). This project
officially supports node v6.x and later.