Beginning implementation of the planned API endpoints.

api/src/main/sql/migrations/20190214122514-initial-schema-up.sql

@@ -4,7 +4,7 @@ create extension if not exists "uuid-ossp";
 create table "users" (
   id uuid default uuid_generate_v4() primary key,
   display_name varchar not null,
-  email varchar not null,
+  email varchar not null unique,
   hashed_pwd varchar not null
 );