Add the ability to count unique values in a calendar-bounded time period, called Calendargrams

[lukevenediger]

Allow a client to count the number of unique values in a calendar-bounded time period. Allow a client to count uniques for a 5-minute, hour, day, week, day-of-week, month time period. The time period must be specified when the client logs the metric. The calendar used will be based on the server's local time.