sw_vers doesn't work on Linux , how about lsb_release -a ?

[liyiheng]

https://github.com/senorprogrammer/wtf/blob/bf4ab1056f8f50dd8269a2b639ed155c210e83b8/system/system_info.go#L21

[liyiheng]

I don't think it works. Output of lsb_release -a has different keys with sw_vers.
Without tests on other distros, I'm not sure about which keys to use. But it is clear that we should use different keys for Linux.

LSB Version:	1.4
Distributor ID:	Arch
Description:	Arch Linux
Release:	rolling
Codename:	n/a

sysInfo := SystemInfo{
		ProductName:    m["ProductName"],
		ProductVersion: m["ProductVersion"],
		BuildVersion:   m["BuildVersion"],
	}

[liyiheng]

Here is the output on CentOS, I think it's OK to use Distributor ID as ProductName, Description as ProductVersion and Release as BuildVersion. #124

LSB Version:    :core-4.1-amd64:core-4.1-noarch
Distributor ID: CentOS
Description:    CentOS Linux release 7.4.1708 (Core) 
Release:        7.4.1708
Codename:       Core