Fix a few warnings

src/main.rs

@@ -12,11 +12,8 @@ extern crate dotenv;
 extern crate openssl;
 extern crate rocket;
 extern crate rocket_contrib;
-#[feature(custom_attribute)]
 extern crate serde;
 #[macro_use]
-extern crate serde_derive;
-#[macro_use]
 extern crate serde_json;
 
 use diesel::pg::PgConnection;
@@ -32,9 +29,6 @@ mod schema;
 mod routes;
 mod utils;
 
-use db_conn::DbConn;
-use models::instance::*;
-
 type PgPool = Pool<ConnectionManager<PgConnection>>;
 
 /// Initializes a database pool.