Add PropTypes and defautProps to LazyLoadImage.jsx (#3)

Author: Youkyoung.Park

src/components/LazyLoadImage.jsx

@@ -101,13 +101,26 @@ class LazyLoadImage extends React.Component {
 
 LazyLoadImage.propTypes = {
   afterLoad: PropTypes.func,
+  beforeLoad: PropTypes.func,
+  delayMethod: PropTypes.string,
+  delayTime: PropTypes.number,
   effect: PropTypes.string,
-  placeholderSrc: PropTypes.string
+  placeholderSrc: PropTypes.string,
+  threshold: PropTypes.number,
+  visibleByDefault: PropTypes.bool,
+  wrapperClassName: PropTypes.string
 };
 
 LazyLoadImage.defaultProps = {
   afterLoad: () => ({}),
-  effect: ''
+  beforeLoad: () => ({}),
+  delayMethod: 'throttle',
+  delayTime: 300,
+  effect: '',
+  placeholderSrc: '',
+  threshold: 100,
+  visibleByDefault: false,
+  wrapperClassName: ''
 };
 
 export default LazyLoadImage;