adopt refactored vtkTreeHeatmapItem

Slight changes to the Visomics source code to reflect the
corresponding changes to vtkTreeHeatmapItem.  This commit
resolves a segmentation fault that occurred when navigating
to the "dendrogram only" view of a tree + heatmap in Visomics.
Merge branch 'update_tree_view'

* update_tree_view:
  adopt refactored vtkTreeHeatmapItem
change item names in the data browser

Change the way that input data are named within the data browser.
Instead of reflecting the name of the file that they were loaded
from, such data are now named simply after their type (table, tree,
etc).  This makes it easier for us to change the input within a
saved workflow, so that the same workflow can be executed on
different input data.
Merge branch 'remove_hardcoded_paths'

* remove_hardcoded_paths:
  change item names in the data browser
Intial commit of Python R pipeline ..
Add in REST API that calls celery
We don't need to use base64 encoding
Move jobs.py to tasks/vkt/r.y

Better REST URI
Post request shouldn't require positional args
Add JsonCpp
Remove logging
WIP: client side ...