Set up database migrations

models/sql/sessions.sql

@@ -1,5 +0,0 @@
-CREATE TABLE sessions (
-  id SERIAL PRIMARY KEY,
-  user_id INT UNIQUE REFERENCES users (id) ON DELETE CASCADE,
-  token_hash TEXT UNIQUE NOT NULL
-);

models/sql/users.sql

@@ -1,5 +0,0 @@
-CREATE TABLE users (
-  id SERIAL PRIMARY KEY,
-  email TEXT UNIQUE NOT NULL,
-  password_hash TEXT NOT NULL
-);