Add new service classes to create and update project and personal
snippets. These classes are responsible for enforcing restricted
visibility settings for non-admin users.
The goal of suych refactoring is to get rid of observers.
Its much easier to test and code when object creation and all other
related actions done in one class instead of splited across observers,
callbacks etc.
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
