Move rollup.unit.config.js inside test folder, and update path in package.json

package.json

@@ -27,7 +27,7 @@
   },
   "scripts": {
     "build": "rollup -c",
-    "build-test": "rollup -c rollup.unit.config.js",
+    "build-test": "rollup -c test/rollup.unit.config.js",
     "build-uglify": "rollup -c && uglifyjs build/three.js -cm --preamble \"// threejs.org/license\" > build/three.min.js",
     "build-closure": "rollup -c && java -jar utils/build/compiler/closure-compiler-v20160713.jar --warning_level=VERBOSE --jscomp_off=globalThis --jscomp_off=checkTypes --externs utils/build/externs.js --language_in=ECMASCRIPT5_STRICT --js build/three.js --js_output_file build/three.min.js",
     "dev": "rollup -c -w",