NO SUPPLY and NO POWER labels in integral menu.

Makes greyed out buttons less confusing. No more wondering why your turrets won't build. Less newbies confused why they can't make units.

The next step is adding a big red label in the tooltip telling you to connect more generators to the fac.
I was also thinking about some visual feedback about whether the generator you're about to place is close enough to the factory. A green tint on the range texture or something like that.

## Screenshots
![labels1](https://cloud.githubusercontent.com/assets/2241548/4698209/9f232328-5831-11e4-9c33-75101c805e54.jpg)
![labels2](https://cloud.githubusercontent.com/assets/2241548/4698210/9f30cb22-5831-11e4-87fd-594727d3461c.jpg)