Add a Media model

migrations/2018-09-02-111458_create_medias/down.sql

@@ -0,0 +1,2 @@
+-- This file should undo anything in `up.sql`
+DROP TABLE medias;

migrations/2018-09-02-111458_create_medias/up.sql

@@ -0,0 +1,10 @@
+-- Your SQL goes here
+CREATE TABLE medias (
+    id SERIAL PRIMARY KEY,
+    file_path TEXT NOT NULL DEFAULT '',
+    alt_text TEXT NOT NULL DEFAULT '',
+    is_remote BOOLEAN NOT NULL DEFAULT 'f',
+    remote_url TEXT,
+    sensitive BOOLEAN NOT NULL DEFAULT 'f',
+    content_warning TEXT
+)