Model link to lab book is now an image in browser-based activities
Remove permanent floating lab book access

Instead, the lab book is always opened via links on the models.
Refactor browser-based model view code into its own partial

This will make it a little easier to work with in the future
Rename periodic bundle loggers imports to active_imports

Apparently there's some interference when using 'imports' which causes
the imports to be reset every time a new bundle comes in.