Update varify to leverage varify-data-warehouse

Signed-off-by: Don Naegely <naegelyd@gmail.com>
Merge pull request #353 from cbmi/varify-data-warehouse

Update varify to leverage varify-data-warehouse
Fix model import in raw/sources/views.py

Signed-off-by: Don Naegely <naegelyd@gmail.com>
add VCF exporter

Signed-off-by: Adam Wenocur <wenocur@email.chop.edu>