update React TestUtils to 15.0.0

Author: Granze

package.json

@@ -75,7 +75,7 @@
     "postcss-nested": "^1.0.0",
     "postcss-simple-extend": "^1.0.0",
     "postcss-simple-vars": "^1.0.0",
-    "react-addons-test-utils": "^0.14.3",
+    "react-addons-test-utils": "^15.0.0",
     "rimraf": "^2.4.3",
     "run-sequence": "^1.1.2",
     "tap-nyan": "0.0.2",