v0.5.0 reminder

[Chen Yangjian]

• subclass or not subclass in Realm? subclass in Realm but over-writable with opts.Bone
• test cases on object conditions that contain logical operators
• further tests on sequelize adapter
• primaryKey and autoIncrement in type definition
• primaryKey and defaultValue/allowNull in migrations
• change column in SQLite
• default foreignKey in associations
• logger