DS-951 Time calculations when parsing log files

This commit addresses two issues:
- items archived in a month (both as a total and broken down by item types) don't include items archived on the first or last day of the month. The reason is that the SQL query used to determine these numbers excludes the start and end dates, while the code is run using the first and the last day of the month as the start/end dates. 
- dates in the database are in UTC but the dates in the logfiles are in local time. For DSpace instances whose timezone is far away from UTC, items made live very early in the month local time can be counted as the previous month when going by the accession time from the database.