Include full network history around current time.

When requesting historical values with time ranges, always include
full values for buckets that span current time.  (It doesn't make
sense to interpolate partial data.)  Move getTotalData() to return
full Entry objects to prepare for packet counts.

Bug: 4691901
Change-Id: I717bd721be9f1d4a47c4121e46e07a56cb15bbf1