initial grails project

cmd:
grails create-domain-class User
grails create-domain-class Book
grails create-domain-class Own
grails create-domain-class Borrow

grails create-controller User
grails create-controller Book
grails create-controller Own
grails create-controller Borrow

fix DataSource.groovy to support the mysql

grails clean
grails compile-refresh-dependencies

fix the controller to add scaffold
fix the domain to add property and constraints