添加单元测试 (#12)

* 添加单元测试

build/bin/build-entry.js

@@ -11,12 +11,13 @@ var ISNTALL_COMPONENT_TEMPLATE = '  Vue.component({{name}}.name, {{name}});';
 var MAIN_TEMPLATE = `{{include}}
 
 const install = function(Vue) {
+  /* istanbul ignore if */
   if (install.installed) return;
 
 {{install}}
 };
 
-// auto install
+/* istanbul ignore if */
 if (typeof window !== 'undefined' && window.Vue) {
   install(window.Vue);
 }