Use existing file metadata for created and modified dates

NB: this definintely works on OSX. Other operating systems may have
slightly different interpretations of birthtime.

See: https://nodejs.org/api/fs.html#fs_class_fs_stats

browser/main/NoteList/index.js

@@ -584,22 +584,29 @@ class NoteList extends React.Component {
     filepaths.forEach((filepath) => {
       fs.readFile(filepath, (err, data) => {
         if (err) throw Error('File reading error: ', err)
-        const content = data.toString()
+
-        const newNote = {
+        fs.stat(filepath, (err, {mtime, birthtime}) => {
-          content: content,
+          if (err) throw Error('File stat reading error: ', err);
-          folder: folder.key,
+
-          title: markdown.strip(findNoteTitle(content)),
+          const content = data.toString()
-          type: 'MARKDOWN_NOTE'
+          const newNote = {
-        }
+            content: content,
-        dataApi.createNote(storage.key, newNote)
+            folder: folder.key,
-        .then((note) => {
+            title: markdown.strip(findNoteTitle(content)),
-          dispatch({
+            type: 'MARKDOWN_NOTE',
-            type: 'UPDATE_NOTE',
+            createdAt: birthtime,
-            note: note
+            updatedAt: mtime
-          })
+          }
-          hashHistory.push({
+          dataApi.createNote(storage.key, newNote)
-            pathname: location.pathname,
+          .then((note) => {
-            query: {key: getNoteKey(note)}
+            dispatch({
+              type: 'UPDATE_NOTE',
+              note: note
+            })
+            hashHistory.push({
+              pathname: location.pathname,
+              query: {key: getNoteKey(note)}
+            })
           })
         })
       })

browser/main/lib/dataApi/createNote.js

@@ -66,12 +66,12 @@ function createNote (storageKey, input) {
           }
         }
       }
-      const noteData = Object.assign({}, input, {
+      const noteData = Object.assign({}, {
         key,
         createdAt: new Date(),
         updatedAt: new Date(),
         storage: storageKey
-      })
+      }, input)
 
       CSON.writeFileSync(path.join(storage.path, 'notes', key + '.cson'), _.omit(noteData, ['key', 'storage']))