Don't make .babelrc a requirement. (#103)

* Don't make .babelrc a requirement.

If you don't have a .babelrc file in your project you still get babel warning: "You are trying to use "babel". babel-preset-es2015, babel-runtime and babel-plugin-transform-runtime are missing."

* Move only comparison to exported function.

lib/compilers/babel.js

@@ -23,20 +23,20 @@ function getBabelRc () {
   return rc
 }
 
-if (babelOptions === defaultBabelOptions) {
-  try {
-    ensureRequire('babel', ['babel-preset-es2015', 'babel-runtime', 'babel-plugin-transform-runtime'])
-  } catch (e) {
-    console.error(e.message)
-    console.error(
-      '\n^^^ You are seeing this because you are using Vueify\'s default babel ' +
-      'configuration. You can override this with .babelrc or the babel option ' +
-      'in vue.config.js.'
-    )
+module.exports = function (raw, cb, compiler, filePath) {
+  if (babelOptions === defaultBabelOptions) {
+    try {
+      ensureRequire('babel', ['babel-preset-es2015', 'babel-runtime', 'babel-plugin-transform-runtime'])
+    } catch (e) {
+      console.error(e.message)
+      console.error(
+        '\n^^^ You are seeing this because you are using Vueify\'s default babel ' +
+        'configuration. You can override this with .babelrc or the babel option ' +
+        'in vue.config.js.'
+      )
+    }
   }
-}
 
-module.exports = function (raw, cb, compiler, filePath) {
   try {
     var babel = require('babel-core')
     var options = assign({