refactor code to use Shrinkwraprs and diesel-derive-newtype (#598)

* add shrinkwraprs and implement Id thru it

This also means we can automatically convert Id to String without using
.into()!

* cleanup with the help of clippy!

* cleanup with the help of cargo fmt!

* remove extra block

* Shrinkwrap Page, ContentLen and RemoteForm

* translations

plume-models/src/posts.rs

@@ -642,7 +642,7 @@ impl FromId<PlumeRocket> for Post {
             .attributed_to_link_vec::<Id>()?
             .into_iter()
             .fold((None, vec![]), |(blog, mut authors), link| {
-                let url: String = link.into();
+                let url = link;
                 match User::from_id(&c, &url, None) {
                     Ok(u) => {
                         authors.push(u);