Update README.md
Update README.md
Fix example bootstrap if launch into composer vendor
Fix phpredis example
Merge pull request #63 from jeromemacias/patch-1

Fix example bootstrap if launch into composer vendor
Merge pull request #64 from jeromemacias/patch-2

Fix phpredis example
Merge pull request #66 from henrikbjorn/master

Invoker implements Callable
Middleware

Middleware are the Extension point for integration of other services
like Spork, StatsD, Rollbar and so on. By default there exists 4
middlewares. 2 of them are internal.

Internal

* Queue. Every queue implements Middleware and its function is for
queueing.
* Invoker.

External

* ErrorLogMiddleware. Uses error_log to report exceptions from
consumers.
* LoggerMiddleware. Uses PSR-3 to log different aspect of consuming and
producing of messages.