Refactored json storage

lib/repositories/metadata/models/budget.dart

@@ -0,0 +1,21 @@
+class Budget {
+  bool monthly;
+  double value;
+
+  Budget({
+    this.monthly = false,
+    this.value = 0.0,
+  });
+
+  factory Budget.fromJson(Map<String, dynamic> json) {
+    return Budget(
+      monthly: json['monthly'],
+      value: double.parse(json['value']),
+    );
+  }
+
+  Map<String, String> toJson() => {
+    'monthly': monthly.toString(),
+    'value': value.toString(),
+  };
+}