Added member state migration and model.

app/MemberState.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace App;
+
+use Illuminate\Database\Eloquent\Model;
+
+class MemberState extends Model
+{
+    //
+}

database/migrations/2018_09_07_083646_create_member_states_table.php

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+<?php
+
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Migrations\Migration;
+
+class CreateMemberStatesTable extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::create('member_states', function (Blueprint $table) {
+            $table->increments('id');
+            
+            // Ther person id the member dates belong to.
+            // IF the corresponding person is deleted, all the member dates are
+            // deleted, too.
+            $table->integer('person_id')->unsigned();
+            $table->foreign('person_id')->references('id')->on('people')
+                  ->onDelete('cascade');
+
+            // The date of joining
+            $table->date('joining_date');
+
+            // The date of leaving
+            $table->date('leaving_date')->nullable();
+
+            $table->timestamps();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::dropIfExists('member_states');
+    }
+}