[Bug Report] FreeBSD doesn't have native libraries for changing volume

### Bug Description

java.lang.IllegalArgumentException: Unknown operating system: FreeBSD

### Steps to Reproduce

1. play a song

### Expected Result

play music

### Debug Output

[10:27:20] [INFO] [NativeLibraryLoader]: Native library libmpg123-0: loading with filter com.sedmelluq.discord.lavaplayer.natives.ConnectorNativeLibLoader$$Lambda$289/0x000000081d304418@44783e26
[10:27:20] [INFO] [NativeLibraryLoader]: Native library libmpg123-0: could not detect sytem type, but system filter is com.sedmelluq.discord.lavaplayer.natives.ConnectorNativeLibLoader$$Lambda$289/0x000000081d304418@44783e26 - assuming it does not match and skipping library.
[10:27:20] [INFO] [NativeLibraryLoader]: Native library connector: loading with filter null
[10:27:20] [ERROR] [NativeLibraryLoader]: Native library connector: loading failed.
java.lang.IllegalArgumentException: Unknown operating system: FreeBSD
at com.sedmelluq.lava.common.natives.architecture.DefaultOperatingSystemTypes.detect(DefaultOperatingSystemTypes.java:46)
at com.sedmelluq.lava.common.natives.architecture.SystemType.detect(SystemType.java:44)
at com.sedmelluq.lava.common.natives.NativeLibraryLoader.detectMatchingSystemType(NativeLibraryLoader.java:180)

### Additional Info

I've been using this bot on this operating system for about 5 months

FreeBSD freebsd 11.2-RELEASE-p3 FreeBSD 11.2-RELEASE-p3 #0: Thu Sep 6 07:14:16 UTC 2018 root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC amd64

EDIT--

root@freebsd:/home/tiago # cat serversettings.json
{
"693196163922264065": {},
"690643625524068412": {},
"690649853327310850": {},
"689485187729719450": {"volume": 45}
}root@freebsd:/home/tiago # vi serversettings.json
{
"693196163922264065": {},
"690643625524068412": {},
"690649853327310850": {},
}

after I deleted the volume directive the bot started working again

### Checklist

- [X] I have looked for information about this [within the documentation](https://jmusicbot.com/)
- [X] I have searched for similar issues [on the issues page](https://github.com/jagrosh/MusicBot/issues?q=is%3Aissue)
- [X] I am running the latest version of the bot: 

Start at DefaultOperatingSystemTypes.java:46, where FreeBSD is rejected, then trace detection through SystemType.java and NativeLibraryLoader.java. Determine how the connector native library handles operating-system types and verify that enabling volume settings on FreeBSD no longer fails during native loading.

Written by the indexing model from the issue text.