Integration of NCS Pathways with Settings

[gkahiu]

When a new base directory is defined in settings, the system will automatically create a sub-directory named ncs_pathways under BASE_DIR. NCS pathways datasets should be copied to this sub-directory. File names (NOT absolute path) should match those defined in the path key for each NCS pathway configuration in the DEFAULT_NCS_PATHWAYS variable in the definitions.defaults module.

For now, the path attribute is empty until I get access to the datasets.