Fix missing argument shift in ContextNodeModel.create

Update ContextNodeModel branch validation to not be strict, i.e.
no children are required.
Update to Marionette 1.0.3
Add missing change event proxy from children to parent
Change ContextTree to bind to public collection

This ensures _only_ valid and saved models will be present.
Remove caching of workspace concept forms

This was causing an issue when re-showing the views in the main
region. Event handlers were not being rebound so none of the
buttons worked. This seems like an inconsistency in Marionette since
regions close views, but do not attempt to re-render the view when
shown again.
Only re-fetch stats if the collection is empty

Since this lives on the field model, these stats will remain after
the first fetch.
Infograph bar style tweaks