Update sessions migration

Author: jbrooksuk

database/migrations/2016_04_05_142933_create_sessions_table.php

@@ -14,12 +14,12 @@
     public function up()
     {
         Schema::create('sessions', function (Blueprint $table) {
-            $table->string('id')->unique();
-            $table->integer('user_id')->nullable();
+            $table->string('id')->primary();
+            $table->foreignId('user_id')->nullable()->index();
             $table->string('ip_address', 45)->nullable();
             $table->text('user_agent')->nullable();
-            $table->text('payload');
-            $table->integer('last_activity');
+            $table->longText('payload');
+            $table->integer('last_activity')->index();
         });
     }