Fix missing reference to router options.id
Clean up and simplify logic for context nodes

The `create` option on fetch now must be a node type of either
'branch', 'condition' or 'composite' to choose the correct constructor.

Fix missing call to root.save() prior to saving the ContextModel itself.
This prevented the publicAttributes object from every getting updated
before being sent to the server.

Add CONTEXT_SAVE channel to transparently request the session be saved.
Add option to hide field info for a single-field concept

This is prevent redundant information being rendered in the UI since
it is common to create single-field concepts with the same name and
description.
Remove unused main and chart regions

As of e38f66c2 ConceptForm does not render it's own chart, but
simply delegates to the first related field.