This will list the tags along with the number of number of times it is
used.
An optional --noheader flag can be passed after the command to prevent
the header being printed.
e.g.
```
$ kb list-tags
name count
---------------- -----
Linux 2
Authentication 1
Pentesting 1
Enumeration 3
Network Protocol 2
```
```
$ kb list-tags --noheader
Linux 2
Authentication 1
Pentesting 1
Enumeration 3
Network Protocol 2
```
This --noheader flag was also added to the list command
Close#10
