Bug 1023807 - [B2G][Calendar] Month view: Dot does not appears when even...

Added Dots for complete event dates
When the `endDate`  is 'yyyy-mm-ddT00:00:00`, we should use the last second of previous day of `endDate` to instead of it, or we will get wrong `daySpan` from `Calc.daysBetween()`. For example, when `startDate` is `2014-06-10T00:00:00` and `endDate` is `2014-06-18T00:00:00` we don't want to mark the 2014-06-18 date item with the dot icon on month view. Please refer to [1].
[1] https://github.com/mozilla-b2g/gaia/pull/20682/files#diff-fa69b42c7066e08948996ef0e2f0e977R89