minify ES6 modules (#281)

* minify ES6 modules

* oops, don't format scss

Author: mwcz

.prettierignore

@@ -1,5 +1,30 @@
 test
-*.umd.js
-*.min.js
 package.json
 package-lock.json
+
+# Package JS file ignores, variant 1
+#
+# These ignore paths are for when prettier via 'lerna run' which cd's into each
+# package's dir, so they are relative to the package dirs.
+
+/**/*
+!/src/*.js
+!/gulpfile.js
+!/rollup.config.js
+!/*.story.js
+
+# Package JS file ignores, variant 2
+#
+# These ignore paths are for repo-wide prettier runs (like pre-commit hooks)
+# where the working directory is the repo root.
+
+elements/*/**/*
+!elements/*/src/*.js
+!elements/*/gulpfile.js
+!elements/*/rollup.config.js
+!elements/*/*.story.js
+themes/*/**/*
+!themes/*/src/*.js
+!themes/*/gulpfile.js
+!themes/*/rollup.config.js
+!themes/*/*.story.js