Manage navigation with KnpMenuBundle

[netsensei]

Detailed description

Right now, navigation is hard wired throughout different templates. The topnav.html.twig template contains presentation and business logic to render the menu. Depending on the context (logged in/ logged out) different menu items are shown. Then there are the sidebar menu items on "users", "clients" and "tokens".

The result is hard to understand code which is difficult to maintain.

We should move KnpMenuBundle for building and managing menu's.

Context

• Separates business from presentational layer which improves maintainability vastly.
• Introduces flexibility and room to expand how the menu tree is generated while adhering to the SOLID principles.

Possible implementation

Follow the implementation guide to start.

This issue currently depends on #50 which deprecates much of the SharedBundle folder and turns it into a dedicated CoreBundle instead.