[change] StyleSheet: support code-splitting / export smaller API

Quick-fix for code-splitting support by updating the rendered style
sheet in place. Reduce the API to `create`, as the rest is now internal
to the framework.

Fix #34

package.json

@@ -7,7 +7,7 @@
     "dist"
   ],
   "scripts": {
-    "build": "rm -rf ./dist && mkdir dist && babel src -d dist --ignore src/**/__tests__,src/modules/specHelpers",
+    "build": "rm -rf ./dist && mkdir dist && babel src -d dist --ignore **/__tests__,src/modules/specHelpers",
     "build:umd": "webpack --config config/webpack.config.js --sort-assets-by --progress",
     "examples": "webpack-dev-server --config config/webpack.config.example.js --inline --hot --colors --quiet",
     "lint": "eslint config examples src",