Add a model for external apps

Stores their name, website, and credentials

migrations/sqlite/2018-10-19-165450_create_apps/down.sql

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+-- This file should undo anything in `up.sql`
+DROP TABLE apps;

migrations/sqlite/2018-10-19-165450_create_apps/up.sql

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+-- Your SQL goes here
+CREATE TABLE apps (
+    id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+    name TEXT NOT NULL DEFAULT '',
+    client_id TEXT NOT NULL,
+    client_secret TEXT NOT NULL,
+    redirect_uri TEXT,
+    website TEXT,
+    creation_date DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
+);