Blacksmith

------------------------------
* Fix typo in documentations and internals.

------------------------------
* Add parameter proxies parameter in AsyncClientFactory and SyncClientFactory
It allow to configure http proxies for http and https
* Add parameter verify_certificate parameter in AsyncClientFactory and SyncClientFactory
It allow to disable the TLS Certificate check. By default, in case of invalid
certificate, all request are rejected.

------------------------------
* Add support of the Sync version

..important:

Breaking changes:

* Rename all classes that do async with an ``Async`` prefix.
* Services
* Middlewares
* Service Discovery

------------------------------
* Replace circuit breaker implementation.

..important:

Breaking change in the middleware.

Parameter fail_max is now named threshold
Parameter timeout_duration is now named ttl and is a float (number of second).

------------------------------
* Expose the HTTPCachingMiddleware in blacksmith namespace

------------------------------
* Fix case sensitivity in cache header