Using github.com/klauspost/compress package to replace the current Gzip Handler on the API.
We see significant improvements using this handler over the current one as shown in the benchmark added.
Also:
* move selection of compression from `newCompressedResponseWriter` to `*CompressionHandler.ServeHTTP`.
* renaming `compressedResponseWriter` since it now only does one kind of compression.
Signed-off-by: Alan Protasio <alanprot@gmail.com>