+ Badges introduction to database schemas

+ Adding some default empty list values where applicable
neighbors now has a default value of '[]' to enforce the "empty list" constraint on that field

json-api/migrations/2021-05-17-221928_badges/down.sql

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS `badges`;

json-api/migrations/2021-05-17-221928_badges/up.sql

@@ -0,0 +1,6 @@
+CREATE TABLE IF NOT EXISTS `badges`(
+    `id` INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
+    `name` VARCHAR(256) NOT NULL,
+    `color` INTEGER UNSIGNED NOT NULL DEFAULT 0xFFFFFFFF,
+    PRIMARY KEY(`id`)
+);