v0.3.0 - introduce new cost type for paid tax

This release introduces a new cost types, for tax, that was paid to the tax office. If you use this, make sure to set tax to 0% so that net = gross. In a future release, tax and gross will probably be hidden, when expense type is F-Ust.

Upgrade instructions:

• put new files into your installation directory (via git pull or manually)
• run npm run build
• run php artisan db:seed --class=CostTypeSeeder, this is necessary as new cost types are introduced