Add links for CSV reports downloading into fuel-stats UI

[Alexander Kislitsky]

We should have links for downloading fuel-stats CSV into fuel-web UI

Reports list:

 - istallations info: /api/v1/csv/clusters
 - plugins: /api/v1/csv/plugins
 - flavors: /api/v1/csv/flavor
 - images: /api/v1/csv/image
 - keystone_users: /api/v1/csv/keystone_users
 - tenants: /api/v1/csv/tenant
 - vms: /api/v1/csv/vm
 - volumes: /api/v1/csv/volume
 - all reports (can take lot of time): /api/v1/csv/all

All reports supports filtration by dates through get_params: from_date=YYYY-MM-DD to_date=YYYY-MM-DD
Date filters should be added to reports page. I guess default date range should be from_date=current_date - 1 month, to_date=current_date

[Anastasia Palkina (apalkina)]

Verified