deps: Update to a more recent rocket and rust toolchain

With this patch, Plume will be use a more up-to-date revision of
Rocket, that works with nightly-2018-07-17. It may have been able to
make it work with a more recent revision, but it turns out rocket has
introduced several breaking changes so I’d rather fix those.

Besides updating rocket_i18n and rocket_csrf to use the same revision
than Plume, this patch deals with the new implementation of the
Uri<'_> type. It silents a class of warnings, to deal with a change in
rustc which affects diesel. This latter change should be reverted as
soon as diesel releases a new version of its crate.

src/routes/notifications.rs

@@ -22,5 +22,8 @@ fn notifications(conn: DbConn, user: User) -> Template {
 
 #[get("/notifications", rank = 2)]
 fn notifications_auth() -> Flash<Redirect>{
-    utils::requires_login("You need to be logged in order to see your notifications", uri!(notifications))
+    utils::requires_login(
+        "You need to be logged in order to see your notifications",
+        uri!(notifications).into()
+    )
 }