Add base `Resource` scaffold
Closes #13 (closed)
GET /planets/:id/resources GET /planets/:id/resources/:resource_id
[
{
"id": "f5b34539-4bcd-4a3d-b6f2-da2c580eae1c",
"planet_id": "e0448835-cc2d-40ad-b452-45bd7b7778b7",
"resource_id": "7014e90e-7f52-481e-8685-304898348a18",
"max_amount": 1000,
"current_amount": 400
}
]