Update .gitignore to work with monorepo

.gitignore

@@ -1,6 +1,22 @@
-lib
-public
+# node_modules in sub-packages
+packages/*/node_modules
+
+# Generated code
+packages/*/lib
+packages/reporter-treemap/reporter/public
+
+# Vendor code
+packages/reporter-treemap/reporter/client/vendor
+
+# Test fixtures
+packages/*/test/bundles
+packages/*/test/webpack.config.js
+
+# Test results
+packages/*/test/output
+
 samples
+
 node_modules
 npm-debug.log
 lerna-debug.log