Provide more consistent context to Evaporate.js lifecycle hooks

[brycefisher]

For these callbacks we mostly just wrap Evaporate.js:

• onComplete
• onUploadInitiated
• onStart
• onProgress

We should make sure that a consistent set of data is provided to the developer in these callbacks so that they can always determine which file the event is happening on in a consistent way. For instance, we should always provide the s3UploadId or the filename or the file object in these callbacks.