DevKit updates for 2.x branch

[SonataCI]

Subject

I am targeting this branch, because this is BC.

Changelog

### Removed
- support for php 5 and php 7.0

[greg0ire]

Finally! @core23 I had to switch to weak instead of weak_vendors to have this pass, because weak_vendors wrongly thinks that deprecations coming from test/app/cache are non-vendor deprecations, when in fact they are deprecations about core bundle services. dev-kit will re-add the mode, so it would be great to use new service, but I don't know which should be used (the deprecation message does not say in favor of what each service is deprecated). Can you please help with this?