Add artisan setup commands

[antonkomarev]

This PR introduces 2 new Artisan commands designed in #53.

Create database migration which let application model to register as Reacter:

$ php artisan love:setup-reacterable --model="App\User"

Create database migration which let application model to register as Reactant:

$ php artisan love:setup-reactable --model="App\User"

If not all models should be registered as Reacter or Reactant just append --nullable flag to the command.

$ php artisan love:setup-reacterable --model="App\User" --nullable

Note: These commands generates migration files. You need to run migrations manually.

Resolves issues:

• automates setup migrations creation (closes Add console command to add columns to application tables #53)
• fixes tests database migrating (Migration run ordering orchestral/testbench#243 (comment)).