This change allows the admin user to fetch conversation metrics for an account, agents, and filter conversation metrics for a specific agent.
Fixes#4305
- ReportBuilder wasn't using the specified time zone for the timestamp in the
"build" method
- The ReportController spec was calling `Time.zone.today.to_time`, but
`Date#to_time` disregards the zone from `Time.zone` and reverts to the system
time zone.
