Add test for configuration loading

Author: David Hemphill

__tests__/importsConfig.test.js

@@ -0,0 +1,7 @@
+import tailwind from '../src/index'
+import config from '../defaultConfig.js'
+
+test('it can accept a config file', () => {
+  tailwind('./defaultConfig.js')
+  expect(tailwind.defaultConfig()).toEqual(config)
+})