Adding a backbone version of the app.
Created a basic view to handle the list of files.
Bugfix: tangelo.config() works now for non-directory URLs
Continuing to build backbone infrastructure
Added Girder API hook to vis files collection
Improved menu label rendering
Vega view renders selected vega vis now upon selection
Attempting CRUD on Vis model
Separate events for different FileMenu instances
Unsaved and saved vis behave similarly in vis menu
New visualizations are automatically selected (i.e., rendered) upon creation
Edit button works.
Using unified Vis/File model - model contains both girder file info and downloaded vega spec in single model
Uploading works in principle - needs more fine-grained control
Got rid of superfluous "visName" property
Uploading of new vis works properly (modal dialog asks for filename)
Editing/saving works now.
Delete button works properly.
Display of data via ace editor
Dialog prevents creating new vis without selecting a dataset