Add a utility service class for common DateTime operations used in OpenSkedge.

Signed-off-by: Max Fierke <max@maxfierke.com>
Obey the application default time resolution

Signed-off-by: Max Fierke <max@maxfierke.com>
Enabled globally configured start/end hours in scheduling views.

Signed-off-by: Max Fierke <max@maxfierke.com>