Add some feedback when performing some actions (#552)

* Add a way to display flash messages

* Make the flash messages look nice

* Add actual feedback messages

* cargo fmt

* Move flash messages to PlumeRocket

And add trait to convert PlumeRocket to BaseContext

* Remove useless lifetime

src/main.rs

@@ -45,7 +45,6 @@ use plume_models::{
     search::{Searcher as UnmanagedSearcher, SearcherError},
     Connection, Error, CONFIG,
 };
-use rocket::State;
 use rocket_csrf::CsrfFairingBuilder;
 use scheduled_thread_pool::ScheduledThreadPool;
 use std::process::exit;
@@ -69,8 +68,6 @@ include!(concat!(env!("OUT_DIR"), "/templates.rs"));
 
 compile_i18n!();
 
-type Searcher<'a> = State<'a, Arc<UnmanagedSearcher>>;
-
 /// Initializes a database pool.
 fn init_pool() -> Option<DbPool> {
     dotenv::dotenv().ok();