Make tower select look a little better

Range grows outward on select and shrinks inward on deselect
Merge branch 'master' into christian_staging
Tower menu now rotates to face camera

also moved tower scripts to their own folder because wow
Greatly improve tower selection visuals

Added creative commons menu icons, hover animations, and tweaked some other smaller details
Add upgrade tower prefab
Add tower deletion and upgrade functionality

could still be made more robust
Add sounds for upgrade and uninstall

Also animate the uninstall process
Animate tower upgrades, make range circle look less obnoxious
Enemies will now show their gimmick upon reaching their destination