Articles/issue 122 fluent configuration

related to #122.

**this is a very first draft.**
I've found a lot of documents regarding the configuration API all unrelated and not linked to each other.

* `fluent-config-api-v3-v4-intro` aims to be the hat on top of all the others.
* `fluent-config-api-v3-v4` is the entry point that details all the available API and links to all the detailed articles.

in the latter below the line at the end there are a couple of things I do not know how to handle.

Call to action for @dannycohen @SimonCropp @indualagarsamy and @johnsimons: comments and review :-)
Currently I suppose the only transport that has the concept of "express" is MSMQ because by default MSMQ utilies the post & forward behavior. All the other transports connects directly to the remote broker.
Don't no if with V5 and the new Outbox feature the concept of Express will be extended so that if it is an express message it will go directly to the destination queue without passing in the outbox.