Converting to number input types

Kinda hacky but at least gives us nicer number controls and seemingly casts the string values to numbers in the JSON:
```json
{
  "instance_type": "t2.medium",
  "name": "name",
  "instance_count": "2",
  "run_max_time": 700,
  "run_delay": 10,
  "container_name": "containerName",
  "container_url": "containerUrl"
}
```

The `instanceCount` is still a regular olde `<select>` field so that still seems to be a string. We can probably cast these out to Numbers on the server side or later in the client side (or both) when we go to submit the data to the server.
Merge pull request #1 from pdehaan/patch-1

Converting to number input types