Removing SystemDynamicTemplateModel

This introduces an unhealthy dependency on the system, which should
never ordinarily be exposed to components.
Remove inheritance with separate component

Extending the LoginForm component with MenuItems causes a circular
dependency in rendering.
Create a namespace that allows Cider 0.7.0 to call its tests
Essential tweaks to menu
Replaced SystemDynamicTemplateModel with alternative

Depending on the system is considered to be bad practice, so by
splitting the example page from its menu-items into separate components,
we break the dependency cycle and avoid the need to use the system.

The systemref is still established and passed to the system constructor,
because this may be useful for development tools.
Improved project metadata
Releasing

menu 0.5.3
web-template 0.5.2