Revert "Merge Core/AdminBundle and Core/HolidayBundle"

This reverts commit 6ed2fe6ffda7fa961eb3f8e6d9cb5a33020e31e7.
Add "sonata-project/core-bundle" to composer.json
Add missing setName method
Groups support now only sets the admin roles.
Ignore "web/coverage"
Merge CoreHolidayBundle in HolidayCoreBundle
Fixtures