Refactor contextual sequencing

This contains two refactors to the way we handle contextual sequencing.

## Data link contexts
- Include a new attribute for clickstream: ```data-link-context-name``` which allows an author to be explicit of the human readable name of the context the user is entering. This can then be used in consuming UI components.
- Rename ```data-link-context``` to ```data-link-context-path``` to follow the above naming convention.
- Fix sequence module and associated tests to use above patterns

## Facia collection JSON endpoint
- Refactor the ```renderCollection``` controller action to use @janua's shiny new ```CollectionCache.getCollection(id)``` method to directly lookup the colleciotn by it's id.

Both of these additions now makes it extremely easy for any JS module to request a current sequence.  

/cc @stephanfowler @janua