[#15] Bugfix.

This bug will happens when apt_time contains [0, 0] and [1440, 1440].
[0, 0] means that the last appointment ends in the start of the day.
[1440, 1440] means that the next appointment start in the end of the
day. The original code will report false when user's time selection
contains point [0, 0] and [1440, 1440], which is not right.