give concrete a color that is distinguishing from sand
Small Correction to one of the music names.

Taken from Frank Klepacki's Website
Merge pull request #5481 from Generalcamo/patch-8

Small Correction to one of the music names.
Merge pull request #5480 from Mailaender/d2k-concrete-color

Fixed concrete having the same radar color as sand.
Adds RallyPoint to Airfield