Fix spotlight to work with backdrop and UTC

This pull request mainly just switches all timestamps to UTC.

All dates we generate should be UTC as (apparently) the production/preview/staging boxes are all set to UTC and we aren't doing anything crazy with moment timezone.

All dates we receive should be UTC - thanks backdrop.

Tests have been updated to reflect this.

This has been tested with the new backdrop data Rob's work will provide.

Merge of this should be coordinated with the backdrop and ga collector changes