Capture and health text boxes.

- Remade the unit and building prefabs in order to add the textbox for
capture / health points.
- In the unitBase there now is a currentHealth property which need to be
used when increasing and editing the health of an unit. The health
property is now its maximium / full health point.
- Capture text is shown when an building is being captured.
- Health text is shown when the health of an unit is lower then the
maximium / full health.