Remove example class from dist build

Still want to be including this in our tests, so sanity test now runs
against a separate fixture.

__tests__/fixtures/tailwind-input.css

@@ -0,0 +1,10 @@
+@tailwind preflight;
+
+@tailwind utilities;
+
+@responsive {
+    .example {
+        @apply .font-bold;
+        color: config('colors.red');
+    }
+}

__tests__/sanity.test.js

@@ -7,12 +7,12 @@ import tailwind from '../src/index'
  * Tests
  */
 it('generates the right CSS', () => {
-  const input = fs.readFileSync(path.resolve(`${__dirname}/../css/tailwind.css`), 'utf8')
+  const input = fs.readFileSync(path.resolve(`${__dirname}/fixtures/tailwind-input.css`), 'utf8')
 
   return postcss([tailwind()])
     .process(input)
     .then(result => {
-      const expected = fs.readFileSync(path.resolve(`${__dirname}/fixtures/tailwind.css`), 'utf8')
+      const expected = fs.readFileSync(path.resolve(`${__dirname}/fixtures/tailwind-output.css`), 'utf8')
 
       expect(result.css).toBe(expected)
     })

css/tailwind.css

@@ -1,10 +1,3 @@
 @tailwind preflight;
 
 @tailwind utilities;
-
-@responsive {
-    .example {
-        @apply .font-bold;
-        color: config('colors.red');
-    }
-}