WIP feature for uploading EVL service volumetrics.
Failing unit test for parsing EVL service volumetrics.
Parse raw EVL service volumetrics data to normalised data for inserting
to backdrop.
Pass EVL volumetrics tests

Add permissions for test_user to access evl_services_volumetrics bucket.
Make feature test not WIP.
Failing test for EVL service failures upload
Introduce sheets in tabular data upload.

Change CSV and Excel file upload to produce parse tabular input assuming
multiple sheets. This means that the raw data input will be a nesting of
3 lists: sheets -> rows -> values.
Chain filters for EVL uploads
Fill in details for failing Service Failures test
Parse EVL Service Failures
Add evl_services_failures to dev config
Failing test for EVL Channel Volumetrics.
Parse EVL Channel Volumetrics Excel.

Also, make pep8 happy.
Add _id to EVL buckets.
Add logging when Admin UI has an upload error
Merge branch 'master' into evl-volumetrics-upload

Conflicts:
	backdrop/write/admin_ui.py
Rename evl_upload to ev_upload_filters
Merge pull request #130 from alphagov/evl-volumetrics-upload

Evl volumetrics upload