remove use of rust in migration (#704)

* remove use of rust in migration

rewrite use_timelines_for_feed in pure sql
delete tantivy related migration. It will require reintroducing tantivy
initialisation in docs

fix #702

* Fill timeline from migrations

should fix #692 , but probably require some testing

migrations/sqlite/2019-06-24-105533_use_timelines_for_feed/up.sql

@@ -1,17 +1,6 @@
 -- Your SQL goes here
---#!|conn: &Connection, path: &Path| {
---#!	super::timeline::Timeline::new_for_instance(conn, "Local feed".into(), "local".into()).expect("Local feed creation error");
---#!	super::timeline::Timeline::new_for_instance(conn, "Federated feed".into(), "all".into()).expect("Federated feed creation error");
---#!
---#!	for i in 0.. {
---#!		if let Some(users) = super::users::User::get_local_page(conn, (i * 20, (i + 1) * 20)).ok().filter(|l| !l.is_empty()) {
---#!			for u in users {
---#!				super::timeline::Timeline::new_for_user(conn, u.id, "Your feed".into(), format!("followed or author in [ {} ]", u.fqn)).expect("User feed creation error");
---#!			}
---#!		} else {
---#!			break;
---#!		}
---#!	}
---#!
---#!	Ok(())
---#!}
+INSERT INTO timeline_definition (name, query) VALUES
+       ('Local feed', 'local'),
+       ('Federated feed', 'all');
+INSERT INTO timeline_definition (user_id,name,query)
+               select id,'Your feed','followed or ['||fqn||']' from users;