Support Raspbian

[knqyf263]

I tested on Raspbian jessie.

pi@raspberrypi:~ $ lsb_release -a
No LSB modules are available.
Distributor ID:	Raspbian
Description:	Raspbian GNU/Linux 8.0 (jessie)
Release:	8.0
Codename:	jessie

[kotakanbe]

I tested on Ubuntu 16.04, but an error occurred.

[Feb 13 15:18:47] DEBUG [localhost] Panic: runtime error: index out of range on u16

at https://github.com/future-architect/vuls/pull/330/files#diff-44e83f60130e99fae5610fad77771526R70

/etc/issue is empty file

root@be5ade205d00:/# cat /etc/issue

[knqyf263]

I don't know why /etc/issue is empty.
I also tested on Ubuntu 16.04.

root@ce92a2d78205:/# cat /etc/issue
Ubuntu 16.04.1 LTS \n \l

However, I checked the length of array for an unexpected case.
https://github.com/future-architect/vuls/pull/330/files#diff-44e83f60130e99fae5610fad77771526R70

Thanks.

[kotakanbe]

Many Thanks!