[Http Client] Circuit breaker Middleware

[aedart]

Describe the Feature Thus far, the #15 has changed the Http Client a lot. It now supports a true middleware layer, which means that a circuit breaker can be integrated in a much more convenient way. Nonetheless, some configuration will most likely be required by such a middleware and has yet to be developed.

[aedart]

Removed milestone - other tasks, sadly, must take priority over this feature...