Explicitly reset collections on session open

This is necessary due to a change in Backbone 1.0.0+ where collections
will be updated in-place by default (and thus not reset). This ensures
the collection is reset and the 'reset' event fires.

This fixes the issue that caused the collection never to resolve
itself because the 'reset' event did not fire.
Merge branch 'query-workflow' into 86-contextnode
Add explicit BranchNodeModel.save to recurse over childrem

The base ContextNodeMode.save now performs a shallow clone of
`attributes`. This is prevent deep-copying instances. As a result
the BranchNodeModel extends this behavior to recurse over children
and _gather_ their publicAttributes.
Simplify ConceptForm field and chart rendering

Remove nesting of `context` option within `data` object on
FieldChart instances.

One note is that the creation of the chart here may be redundant
since FieldForm can handle creating it's own chart. However the
location of the rendering the chart (i.e. within .concept vs
.field) must be taken into account as well.