Ensure Successful ZIP64 Extraction

[mheggeseth]

Fixed

• Correctly handle ZIP64 format in unzipper.Extract and unzipper.Parse by ensuring that the standard EOCD signature is consumed after seeking to it, preventing the EOCD read from being incorrectly offset by 4 bytes.
• Emit FILE_ENDED error from PullStream for any pull that goes beyond EOF whether we've reached the central directory (f.k.a. self.__ended==true) or not.

Misc

• Commented/skipped tests that rely on an S3 bucket that no longer seems to be accessible.

Fixes #243

[mtinnes]

any chance this can get merged soon?