Make info.yaml app icon and name optional

Both icon and name fields in the info.yaml configuration file are required, however their usefulness only depends on the system UI implementation. In some cases, one app could expose more than one menu item, thus the system UI needs to rely on other data (e.g. the applicationProperties)

Currently, we need to use a dummy filename (icon: no_icon.png), else the application manager will fail to load. It would be cleaner if the application manager doesn't require these 2 fields, so we don't need to put any value in the info.yaml file.