Add ability to set the sample per route

Currently there is no way to set different player samples per route.
This PR add the ability to set the path to a txt file containing the desired sample for the route.

```
  - domain: example.com
    servers:
    - hub1
    - hub2
    motd: Example Custom MOTD
    sample: exampleSample.txt
  - domain: hub.exmaple.com
    server: hub
    motds:
    - Example MOTD 1
    - Example MOTD 2
    sample: hubSample.txt
```