chore(deps): cumulative react@15 (#6681)

* address node-fetch vulnerability

react@15.7.0
react-dom@15.7.0
create-react-class@15.6.3

* npm audit now provides semver warning of breaking change

package.json

@@ -75,10 +75,10 @@
     "memoizee": "^0.4.12",
     "prop-types": "^15.7.2",
     "randombytes": "^2.1.0",
-    "react": "^15.6.2",
+    "react": "=15.7.0",
     "react-copy-to-clipboard": "5.0.1",
     "react-debounce-input": "^3.2.0",
-    "react-dom": "^15.6.2",
+    "react-dom": "=15.7.0",
     "react-immutable-proptypes": "2.1.0",
     "react-immutable-pure-component": "^1.1.1",
     "react-inspector": "^2.3.0",