Implement Indicator and IndicatorManager classes

This is still a WIP until I figure out what the MIDlet I'm testing is actually doing on a real phone.
This function (and the Indicator constructor) are called at startup.
So I think what the MIDlet does is:
Indicator indicator = new Indicator(0, image);
IndicatorManager indicatorManager = IndicatorManager.getIndicatorManager();
indicatorManager.appendIndicator(indicator, false);

I guess the IndicatorManager is needed when you have multiple MIDlets running simultaneously in the background, so each one needs an indicator.