Drop diesel as external crate (for now); fixes warning

server/src/main.rs

@@ -1,9 +1,6 @@
 #![recursion_limit = "256"]
 #![feature(proc_macro_hygiene, decl_macro)]
 
-#[macro_use]
-extern crate diesel;
-
 use rocket::{catchers, routes, Rocket};
 use rocket_contrib::serve::StaticFiles;