Use proper DateTime (from chrono) instead of i64

Use the local timezone for now.

For the proper implementation the client's timezone should be obtained,
either from users preferences, or from the browser.

client/src/lib.rs

@@ -61,15 +61,15 @@ fn update(msg: Msg, model: &mut Model, orders: &mut impl Orders<Msg>) {
 }
 
 fn commit_to_dom<T>(commit: &SocialCommit) -> Vec<Node<T>> {
-    nodes![
+    nodes![div![
         p!(format!(
             "Author: {} <{}>",
             commit.author.name, commit.author.email
         )),
-        p!(format!("Date: {}", commit.time)),
+        span!(format!("Date: {}", commit.time)),
         p!(format!("    {}", commit.message.replace("\n", "\n    "))),
         hr![],
-    ]
+    ]]
 }
 fn tree_entry_to_dom<T>(te: &SocialTreeEntry) -> Vec<Node<T>> {
     nodes![p![format!("{:o} | {}", te.filemode, te.name)], hr![],]