Allow script long options

[LukeShirnia]

Resolves issue #5

Usage: disk_usage_check.sh [-f] [-b] [-h]
           -f, --filesystem <filesystem>  Specify a Filesystem
           -b, --bbcode                   Print with bbcode
           -h, --help                     Print help (usage)

Invalid long option

$ bash disk_usage_check.sh --random
Invalid option: --random
Usage: disk_usage_check.sh [-f] [-b] [-h]
           -f, --filesystem <filesystem>  Specify a Filesystem
           -b, --bbcode                   Print with bbcode
           -h, --help                     Print help (usage)

Invalid short option

$ bash disk_usage_check.sh -r
Invalid option: r
Usage: disk_usage_check.sh [-f] [-b] [-h]
           -f, --filesystem <filesystem>  Specify a Filesystem
           -b, --bbcode                   Print with bbcode
           -h, --help                     Print help (usage)

Combination of short and long options:

$ bash disk_usage_check.sh --bbcode -f /boot


============================================================ 
 	 == /boot Filesystem Information == 
============================================================ 

[code]
Filesystem     Type  Size  Used Avail Use% Mounted on
/dev/sda6      ext4  3.9G  284M  3.4G   8% /boot

Filesystem     Type Inodes IUsed  IFree IUse% Mounted on
/dev/sda6      ext4 258560   416 258144    1% /boot
[/code]

============================================================ 
 	 == Largest Directories == 
============================================================ 

[code]
236M  total
236M  /boot
16K   /boot/lost+found
8.0K  /boot/loader
4.0K  /boot/loader/entries
4.0K  /boot/grub2
4.0K  /boot/efi
1.1M  /boot/extlinux
[/code]

============================================================ 
 	 == Largest Files == 
============================================================ 

[code]
79.54M  /boot/initramfs-0-rescue-bcb9ae7409a94ea48a6dc8a5fe6c8077.img
32.86M  /boot/initramfs-5.8.6-201.fc32.x86_64.img
32.54M  /boot/initramfs-5.7.15-100.fc31.x86_64.img
32.43M  /boot/initramfs-5.7.11-100.fc31.x86_64.img
11.12M  /boot/vmlinuz-5.8.6-201.fc32.x86_64
10.32M  /boot/vmlinuz-5.7.11-100.fc31.x86_64
10.32M  /boot/vmlinuz-5.7.15-100.fc31.x86_64
8.89M   /boot/vmlinuz-0-rescue-bcb9ae7409a94ea48a6dc8a5fe6c8077
5.08M   /boot/System.map-5.8.6-201.fc32.x86_64
4.93M   /boot/System.map-5.7.15-100.fc31.x86_64
4.93M   /boot/System.map-5.7.11-100.fc31.x86_64
0.22M   /boot/config-5.8.6-201.fc32.x86_64
0.21M   /boot/config-5.7.15-100.fc31.x86_64
0.21M   /boot/config-5.7.11-100.fc31.x86_64
0.18M   /boot/elf-memtest86+-5.01
0.18M   /boot/memtest86+-5.01
0.18M   /boot/extlinux/libcom32.c32
0.16M   /boot/extlinux/hdt.c32
0.11M   /boot/extlinux/ldlinux.c32
0.10M   /boot/extlinux/liblua.c32
[/code]

============================================================ 
 	 == OK Check List == 
============================================================ 

The following have been checked and are ok: 

[OK]      No Volume groups (vgs) found
[OK]      No open DELETED files over 500MB
[WARNING] /home/rack does not appear to exist

============================================================

Single long option

$ bash disk_usage_check.sh --filesystem /boot


============================================================ 
 	 == /boot Filesystem Information == 
============================================================ 

Filesystem     Type  Size  Used Avail Use% Mounted on
/dev/sda6      ext4  3.9G  284M  3.4G   8% /boot

Filesystem     Type Inodes IUsed  IFree IUse% Mounted on
/dev/sda6      ext4 258560   416 258144    1% /boot

============================================================ 
 	 == Largest Directories == 
============================================================ 

236M  total
236M  /boot
16K   /boot/lost+found
8.0K  /boot/loader
4.0K  /boot/loader/entries
4.0K  /boot/grub2
4.0K  /boot/efi
1.1M  /boot/extlinux

============================================================ 
 	 == Largest Files == 
============================================================ 

79.54M  /boot/initramfs-0-rescue-bcb9ae7409a94ea48a6dc8a5fe6c8077.img
32.86M  /boot/initramfs-5.8.6-201.fc32.x86_64.img
32.54M  /boot/initramfs-5.7.15-100.fc31.x86_64.img
32.43M  /boot/initramfs-5.7.11-100.fc31.x86_64.img
11.12M  /boot/vmlinuz-5.8.6-201.fc32.x86_64
10.32M  /boot/vmlinuz-5.7.11-100.fc31.x86_64
10.32M  /boot/vmlinuz-5.7.15-100.fc31.x86_64
8.89M   /boot/vmlinuz-0-rescue-bcb9ae7409a94ea48a6dc8a5fe6c8077
5.08M   /boot/System.map-5.8.6-201.fc32.x86_64
4.93M   /boot/System.map-5.7.15-100.fc31.x86_64
4.93M   /boot/System.map-5.7.11-100.fc31.x86_64
0.22M   /boot/config-5.8.6-201.fc32.x86_64
0.21M   /boot/config-5.7.15-100.fc31.x86_64
0.21M   /boot/config-5.7.11-100.fc31.x86_64
0.18M   /boot/elf-memtest86+-5.01
0.18M   /boot/memtest86+-5.01
0.18M   /boot/extlinux/libcom32.c32
0.16M   /boot/extlinux/hdt.c32
0.11M   /boot/extlinux/ldlinux.c32
0.10M   /boot/extlinux/liblua.c32

============================================================ 
 	 == OK Check List == 
============================================================ 

The following have been checked and are ok: 

[OK]      No Volume groups (vgs) found
[OK]      No open DELETED files over 500MB
[WARNING] /home/rack does not appear to exist

============================================================