feat: Payment system with voucher cards.

feat: Design with inversion dependency injection architecture.
feat: Prettier http middleware.
feat: Re-write items categories with preferred accounts.

server/src/system/migrations/20200823234434_create_subscription_plan_feature.js

@@ -0,0 +1,17 @@
+
+exports.up = function(knex) {
+  return knex.schema.createTable('subscription_plan_features', table => {
+    table.increments();
+
+    table.integer('plan_id').unsigned();
+    table.string('slug');
+    table.string('name');
+    table.string('description');
+
+    table.timestamps();
+  });
+};
+
+exports.down = function(knex) {
+  return knex.schema.dropTableIfExists('subscription_plan_features');
+};