Implement database feature

A simple JSON-based database that works through loading full self-copy
into the memory. Should be more than enough for the needs of kf modding.

fixtures/database/administration/registered.json

@@ -0,0 +1,13 @@
+{
+    "76561198025127722": {
+        "allowed_ips": ["127.0.0.1", "192.168.0.100"],
+        "groups": ["admin"],
+        "ip_lock": true,
+        "password_hash": "fce798e0804dfb217f929bdba26745024f37f6b6ba7406f3775176e20dd5089d"
+    },
+    "76561198044316328": {
+        "groups": ["admin"],
+        "ip_lock": false,
+        "password_hash": "fce798e0804dfb217f929bdba26745024f37f6b6ba7406f3775176e20dd5089d"
+    }
+}