Updated whitelist mgmt with the following changes:

- Modified initial JSON structure
- Changed @@whitelist.json view to dataset context
- Added select for @@manage-whitelist with the available datacubes
- Added js for @@manage-whitelist options display based on datacube selection
- WIP: updated import/export feature to support contextual whitelist settings
Updated whitelist implementation:

- Made export to xml view to be contextual
- Properly set the whitelist property when importing xml and no previous settings saved
- Hide table when no whitelist settings are present for the selected dataset
Added upgrade step for migrating whitelist settings for each datacube
Use an empty WHITELIST dictionary as default
Updated whitelist mgmt with the followint changes:

- Drop hardcoded labels/headers for whitelist settings
- Allow import of xls files with any number of columns. The first row cells
  values will be used as attributes/labels