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

src/main.rs

@@ -62,6 +62,8 @@ mod mail;
 #[macro_use]
 mod template_utils;
 mod routes;
+#[macro_use]
+extern crate shrinkwraprs;
 #[cfg(feature = "test")]
 mod test_routes;