Create Ushahidi\App namespace for app code not tied to Kohana

[rjmackay]

• Currently we use application/ for implementation specific code. However this also ties things to Kohana
• For code which isn't tied to kohana but is implementation specific it'd be good to move into src/App so we can use PSR4 etc

[rjmackay]

This might be a good idea as prep for the move away from Kohana #1372

[rjmackay]

I'm trying to sort out a naming scheme for platform that avoids having an Ushahidi\App layer since that'll get confusing with Laravels typical App namespacing. I'm consider something like

Ushahidi\Core : Domain layer has entities, repo interfaces, usecase
Ushahidi\Infrastructure or just Ushahidi\Infra : concrete repos, validators, tooling (what I had started moving into Ushahidi\App)
Ushahidi\App .. whats normally in laravels App : controllers, routes, other laravel specific wiring

I'd also like to group things by model a bit more so you would have clear Post, Survey, User etc folders. That would put the Post validator, repo, formatter etc alongside each other.. just not quite sure how to manage that with the Domain / Infra / App split.