Big repository reorganization

The code is divided in three crates:
- plume-common, for the ActivityPub module, and some common utils
- plume-models, for the models and database-related code
- plume, the app itself

This new organization will allow to test it more easily, but also to create other tools that only reuse a little part of
the code (for instance a Wordpress import tool, that would just use the plume-models crate)

src/routes/well_known.rs

@@ -3,10 +3,8 @@ use rocket::response::Content;
 use serde_json;
 use webfinger::*;
 
-use BASE_URL;
-use activity_pub::ap_url;
-use db_conn::DbConn;
-use models::{blogs::Blog, users::User};
+use plume_common::activity_pub::ap_url;
+use plume_models::{BASE_URL, db_conn::DbConn, blogs::Blog, users::User};
 
 #[get("/.well-known/nodeinfo")]
 fn nodeinfo() -> Content<String> {