[fix] Crash when turning the screen

[fix] Week reference

[add] Insert button, Remove Button

[fix] Return null when db is empty

[add] Delete method, FindFirst method

[add] Update adapter when db changes

[fix] Two-way notification

[fix] MainAdapter in generics of RecyclerView.Adapter

[add] Custom RecyclerView Adapter

[add] AndroidDesignSupportLibrary

[fix] Insert person

[add] PersonRealmHelper

[add] BaseRealmHelper

[add] Init realm, Realm set default configuration

[add] Application class

[add] MainViewModel

[add] Enable databinding, Kapt

[add] Realm

[add] Android Architecture Components for Lifecycles, LiveData, and ViewModel

[add] project