Time selection for web downloads

[klpoland]

Select times for web download:

• Add time selection helper functions
• Integrate slider JS package for range slider UI
• Dynamic labels to indicate number of files and time start and end

[semanticdiff-com]

Review changes with  

Changed Files

File	Status
gateway/sds_gateway/api_methods/tasks.py	27% smaller
gateway/sds_gateway/templates/users/partials/web_download_modal.html	22% smaller
gateway/sds_gateway/static/js/file-list.js	13% smaller
gateway/sds_gateway/api_methods/serializers/capture_serializers.py	4% smaller
gateway/sds_gateway/templates/users/file_list.html	2% smaller
gateway/sds_gateway/api_methods/helpers/temporal_filtering.py	0% smaller
gateway/sds_gateway/static/js/actions/DownloadActionManager.js	0% smaller
gateway/sds_gateway/templates/base.html	0% smaller
gateway/sds_gateway/templates/users/dataset_list.html	0% smaller
gateway/sds_gateway/templates/users/partials/captures_page_table.html	Unsupported file format
gateway/sds_gateway/templates/users/published_datasets_list.html	0% smaller
gateway/sds_gateway/users/views.py	0% smaller