API Feature - Implement GZIP for POST/PUT

[Ant-hem]

The engine is introducing a new feature allowing to optionally compress request payloads (ie. POST/PUT body, http or https).

To test it:

Perform a saveObject with the content encoded with GZIP. Don't forget to add: "Content-Encoding: gzip" as a header.

We will discuss a specification for a more detailed implementation. Like adding a enableGZIP flag in client's configuration.

[aseure]

Specs available here https://github.com/algolia/algoliasearch-client-specs-internal/issues/30