Introduce optional HTTP client caching

[mantzas]

Is your feature request related to a problem? Please describe

Ticket #128 will introduce optionally server-side HTTP caching.
In order to avoid unnecessarily HTTP server roundtrips, the client can follow the caching instructions from the server, if any exist, and implement a local cache that follows these instructions.

Describe the solution

• Introduce an optional cache to the HTTP client by using the cache from Introduce a generic cache package #127
• Make sure we are following issue Introduce HTTP server side caching #128 which follows the RFC

[drakos74]

i would like to work on this, if everyone is ok with it

[drakos74]

just for consistency , RFC for headers : https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control

[drakos74]

On it ...

[drakos74]

With the server implementation merged (#128), if it's ok ...
i ll pick up this one next ...