Revert "feat: use named exports to export helper functions"

This reverts commit 95c3b7d4e8.

src/browser.js

@@ -9,7 +9,7 @@ export { hasMetaInfo } from './shared/hasMetaInfo'
  * Plugin install function.
  * @param {Function} Vue - the Vue constructor.
  */
-function install(Vue, options = {}) {
+function VueMeta(Vue, options = {}) {
   options = setOptions(options)
 
   Vue.prototype.$meta = $meta(options)
@@ -17,13 +17,12 @@ function install(Vue, options = {}) {
   Vue.mixin(createMixin(Vue, options))
 }
 
+VueMeta.version = version
+
 // automatic install
 if (!isUndefined(window) && !isUndefined(window.Vue)) {
   /* istanbul ignore next */
-  install(window.Vue)
+  Vue.use(VueMeta)
 }
 
-export {
-  version,
-  install
-}
+export default VueMeta