Center image diffs (fixes #50)

Author: danvk

webdiff/static/css/style.css

@@ -104,6 +104,7 @@ ul.file-list {
 }
 .image-diff {
   display: table;
+  margin: 0px auto;
 }
 .swipe input {
   width: 100%;

webdiff/static/js/components.jsx

@@ -273,7 +273,7 @@ var CodeDiff = React.createClass({
   },
   render: function() {
     return (
-      <div style={{display: 'table'}}>
+      <div>
         <NoChanges filePair={this.props.filePair} />
         <div ref="codediff" key={this.props.filePair.idx}>Loading&hellip;</div>
       </div>