Enable/disable videos based on time of day

[klarrieu]

This PR allows videos to be enabled/disabled based on time of day. This may be desired to avoid showing videos with bright blue or white light at night (e.g. underwater scenes), or to have day/night scenes play at corresponding day/night time. The following changes were made:

• converted video settings (in settings.xml) from boolean (enabled/disabled) to integer with the following options:
  • 0: On
  • 1: Day Only
  • 2: Night Only
  • 3: Off
• The corresponding labels for these new options have also been added to the language strings.po files.
• These settings are compared with the system time as parsed out in resources/lib/playlist.py to determine whether to play a video when the screensaver is invoked.