Implement ZipWriter for quickly writing ZipFiles.

The ZipWriter implementation exposes a stateful interface that allows
bytes of data to be streamed in as they arrive. ZipEntries can be
compressed and/or aligned on a 32-bit boundary for mmapping at runtime.

Change-Id: I43ac9e661aa5022f00d9e12b247c4314d61c441c
6 files changed