npm 5 auto-prunes on install, which breaks our react behavior.

Ref: npm/npm#16853

package.json

@@ -21,11 +21,11 @@
     "test:env": "sh ./example-test.sh",
     "test:all": "npm run react:13 && npm run test:only && npm run react:14 && npm run test:only && npm run react:15.4 && npm run test:only && npm run react:15 && npm run test:only",
     "clean-local-npm": "rimraf node_modules/.bin/npm node_modules/.bin/npm.cmd",
-    "react:clean": "npm run clean-local-npm && rimraf node_modules/react node_modules/react-dom node_modules/react-addons-test-utils node_modules/react-test-renderer",
-    "react:13": "npm run react:clean && npm i --no-save react@0.13 && npm install",
-    "react:14": "npm run react:clean && npm i --no-save react@0.14 react-dom@0.14 react-addons-test-utils@0.14 && npm install",
-    "react:15.4": "npm run react:clean && npm i --no-save react@15.4 react-dom@15.4 react-addons-test-utils@15.4 && npm install",
-    "react:15": "npm run react:clean && npm i --no-save react@15 react-dom@15 create-react-class@15 react-test-renderer@^15.5.4 && npm install",
+    "react:clean": "npm run clean-local-npm && rimraf node_modules/react node_modules/react-dom node_modules/react-addons-test-utils node_modules/react-test-renderer && npm prune",
+    "react:13": "npm run react:clean && npm install && npm i --no-save react@0.13",
+    "react:14": "npm run react:clean && npm install && npm i --no-save react@0.14 react-dom@0.14 react-addons-test-utils@0.14",
+    "react:15.4": "npm run react:clean && npm install && npm i --no-save react@15.4 react-dom@15.4 react-addons-test-utils@15.4",
+    "react:15": "npm run react:clean && npm install && npm i --no-save react@15 react-dom@15 create-react-class@15 react-test-renderer@^15.5.4",
     "docs:clean": "rimraf _book",
     "docs:prepare": "gitbook install",
     "docs:build": "npm run docs:prepare && gitbook build",