Provide documentation for the accumulated changes towards 4.0

[Xerkus]

Series of pull requests containing work towards next major MVC release will not provide documentation updates as part of those PRs due to overlapping nature of the changes and pending documentation rework (tracked in #55) in order to save effort that would otherwise be wasted.

This issue tracks PRs that must be documented before release could be made.

• Drop module manager and add support for config aggregator #56
• Drop ApplicationInterface #59
• Extract default listeners from Application #161
• Drop request and response from Application and bootstrap event #162