Google Cloud Storage supports chunked uploads

Google Cloud Storage supports chunked encoding for uploads. (Link: https://cloud.google.com/storage/docs/streaming)

We enabled this and saw a 2-4x performance improvement on upload times (mainly because we didn't have to buffer the whole file)

GoogleStorageDriver.supports_chunked_encoding is set to False currently - setting it to True results in a large performance increase

Changes required:

• Change `supports_chunked_encoding` to True
• Minor refactor to verify the hash when uploading via stream since we can calculate the hash. Google recommends verifying the hash for a streaming/chunked upload. The current implementation sets verify_hash=False and does not accept it as an argument. There are a variety of ways to fix this - but I'm not sure what would be best.