Set floating flag correctly when placing unit

When moving to the next stage in Cydonia, flying units were still floating in the deployment zone:
![screen023](https://f.cloud.github.com/assets/1824834/1609390/39c3c53a-5541-11e3-986a-4af4a91c49dd.png)

Update stops the floating:
![screen022](https://f.cloud.github.com/assets/1824834/1609392/543f1fa4-5541-11e3-91b8-5e849ed80f54.png)