Splitting the codebase

[Allendar]

As discussed very shortly in the chatroom, I'd like to recommend a new structure for the codebase into different repositories.

Core Siris
--> Plugins
--> Middleware
--> Examples

All the Examples will be moved, corrected (the current ones are mostly broken) and actually be optimized to be more than just a shallow example and only leave performant ones instead of the slow ones.

Plugins (to be debated in #3 still) could get separate instances like github.com/go-siris/plugin-sessiondb.

Middleware could get separate instances like github.com/go-siris/middleware-auth.

The main reason for this is to fully remove base size stress off the core code-base size, dependencies and keep performance as high as possible. Also there's a better separation for tests and code-coverage and it will probably be a lot easier to know if a bug of performance issue is in the core or one of the plugins or middlewares.

Ping @Dexus @godofdream @Andersbiha @theodesp would love your feedback.

[theodesp]

Yes I like the Idea

[Dexus]

I would also remove all the non core stuff to a own repo.
And anything else that need can be imported... as it will be now but from its own repo...