Revert "Add prepare script to force dependency install via npm"

This reverts commit 5659ca5.

Author: tehvgg

package.json

@@ -21,9 +21,6 @@
     "type": "git",
     "url": "https://github.com/createjs/build.git"
   },
-	"scripts": {
-		"prepare": "echo \"PREPARE\""
-	},
   "devDependencies": {
     "babel-core": "^6.26.0",
     "babel-plugin-external-helpers": "^6.22.0",