Automatically merge/load config and migrations

[tobytwigger]

I'm trying to use the revisionable package in another package I'm developing. I'm running into a problem because revisionable requires the config and migrations to be published before it can work.

Since revisionable is running in a package environment, I'm having to override the default service provider, copy the migrations/config to my package and merge them from there since the vendor folder location (i.e. location of the migrations and config in revisionable) isn't constant. This means that there are now two copies of the config and migrations, and any updates won't be reflected in the package.

If we were to call mergeConfigFrom() in the revisionable Service Provider, revisionable would still work even without publishing the config. This also won't affect any old versions since the config is merged.

public function boot()
    {
        $this->publishes([
            __DIR__ . '/../../config/revisionable.php' => config_path('revisionable.php'),
        ], 'config');
        $this->mergeConfigFrom(__DIR__ . '/../../config/revisionable.php', 'revisionable');

        $this->publishes([
            __DIR__ . '/../../migrations/' => database_path('migrations'),
        ], 'migrations');

    }

When migrations are loaded through loadMigrationsFrom(), it can cause problems if you've also published the migrations. We could get around this by not loading them by default, thus encouraging users to publish their own migrations as expected, but allow them to be loaded by setting 'load_migrations' (or similar) in the config to true?

These changes will then allow this package to be used within other packages without affecting current users of the package.