storage: run validation on raw response stream

[stephenplusplus]

Fixes #654

Previously

If a file was uploaded with gzip content encoding, we were computing the hash of the decoded file.

Now

We deliver the decoded file to the user, but compute the hash based on the raw, encoded file contents.

@beshkenadze - it would be awesome if you could try this out to see if the issue you were having is resolved.

[beshkenadze]

If not authorized request (403 error), then there is a exception. ;)

/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/lib/storage/file.js:552
        res.headers['x-goog-hash'].split(',').forEach(function(hash) {
                                  ^
TypeError: Cannot read property 'split' of undefined
    at DestroyableTransform.<anonymous> (/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/lib/storage/file.js:552:35)
    at DestroyableTransform.emit (events.js:107:17)
    at DestroyableTransform.<anonymous> (/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/node_modules/stream-forward/index.js:31:26)
    at DestroyableTransform.<anonymous> (/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/node_modules/stream-forward/node_modules/on-everything/index.js:12:17)
    at DestroyableTransform.obj.(anonymous function) [as emit] (/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/node_modules/stream-forward/node_modules/stubs/index.js:28:10)
    at StreamCache.<anonymous> (/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/node_modules/stream-forward/index.js:31:26)
    at StreamCache.<anonymous> (/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/node_modules/stream-forward/node_modules/on-everything/index.js:12:17)
    at StreamCache.obj.(anonymous function) [as emit] (/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/node_modules/stream-forward/node_modules/stubs/index.js:28:10)
    at Request.<anonymous> (/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/node_modules/stream-forward/index.js:31:26)
    at Request.<anonymous> (/Users/akira/Projects/My/ReviewHub/src/node_modules/gcloud/node_modules/stream-forward/node_modules/on-everything/index.js:12:17)

[beshkenadze]

Otherwise, everything works! Excellent!

[stephenplusplus]

Thanks for testing, and great catch! I'm going to merge this and send a separate PR for the issue you found, as it spawned quite a few changes. (Hope you don't mind if I ping you again once that PR is in :))

[beshkenadze]

@stephenplusplus NP.