错误提示：
Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema. - configuration.module has an unknown property 'loader'. These properties are valid: object { exprContextCritical?, exprContextRecursive?, exprContextRegExp?, exprContextRequest?, loaders?, noParse?, rules?, unknownContextCritical?, unknownContextRecursive?, unknownContextRegExp?, unknownContextRequest?, unsafeCache?, wrappedContextCritical?, wrappedContextRecursive?, wrappedContextRegExp?, strictExportPresence?, strictThisContextOnImports? } -> Options affecting the normal modules (`NormalModuleFactory`).
webpack v2 之后都用rules 了，把module里的那个loaders改成rules
