improve navbar extension

[scampi]

• use $location for knowing on which page the button should be on Sorry there is no need for this, I didn't realize I could inject services when registering the extension
• It would be good if it is possible to pass a controller from the navbar extension. It is then possible to have angular expressions in the template of the extension. The template's content would be dependent on external factors, e.g., the current page being browsed.

[epixa]

Can you elaborate on what you'd like to see here, what the use case is, etc?

[scampi]

@epixa I updated the description.