Report processor code was truncating microseconds

Because we were not specifying a precision when we called
`Time.iso8601`, the report processor was truncating
microseconds from the timestamps of everything in the
reports.

This commit adds an explicit precision so that we don't
lose the microseconds.
Merge pull request #665 from cprice404/bug/burgundy/PE-1461-report-processor-truncating-microseconds

Report processor code was truncating microseconds