write.js - port over to the new Adapter API
write.js - port over to the new Adapter API

Rename process to write.

Also add support for tracking pending writes using pendingWrites
variable - previously, the 'done' was called after first batch of
points, while it should have been called only when all points are
written.

Finally, rewrite the Write function to be an  ES6 class.

juttle/juttle-influx-adapter,juttle/juttle-influx-adapter