Make database creation queueable (#17)

* SOLIDify database creation

* Return the result of fclose in SQLiteDBCreator

* Make database creation queueable

* Add DatabaseCreationTest

* Make comment more descriptive [ci skip]

* Add composer script to copy .env.example to .env

* Minor tweaks

* Fix env section

* Fix DB_PASSWORD for Travis

src/Interfaces/DatabaseCreator.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Stancl\Tenancy\Interfaces;
+
+interface DatabaseCreator
+{
+    /**
+     * Create a database.
+     *
+     * @param string $name Name of the database.
+     * @return void
+     */
+    public function createDatabase(string $name): bool;
+}