Add `shows` command

Howdy, me again :)

## Shows
```
~ rdio current
Now playing: Milla´s Dream / Parov Stelar / The Princess Part One

~ rdio shows
Here are 10 upcoming events for Parov Stelar
San Francisco CA  United States   Mon, 15 Apr 2013 19:00:00 
San Diego         United States   Thu, 18 Apr 2013 19:00:00 
Tucson            United States   Fri, 19 Apr 2013 20:00:00 
Manchester        United Kingdom  Thu, 30 May 2013 19:30:00 
London            United Kingdom  Fri, 31 May 2013 19:30:00 
London            United Kingdom  Sat, 01 Jun 2013 19:30:00 
Scheeßel          Germany         Fri, 21 Jun 2013 14:38:01 
Neuhausen ob Eck  Germany         Fri, 21 Jun 2013 18:11:01 
Paris             France          Fri, 28 Jun 2013 14:17:01 
Hradec Králové    Czech Republic  Tue, 02 Jul 2013 11:24:01 
```

## Options
```
~ rdio shows --help                  
NAME
    shows - Show upcoming events for an artist

SYNOPSIS
    rdio [global options] shows [command options] 

COMMAND OPTIONS
    --artist=arg - (default: none)
    --count=arg  - (default: 10)
```

Oh and since Last.fm is obviously more intelligent than I am, it also autocorrect (and guess) bad artist spelling:

```
~ rdio shows --artist="Mumford and son" --count=2
Here are 2 upcoming events for Mumford & Sons
Ramonville-Saint-Agne  France  Tue, 19 Mar 2013 20:30:00 
Barcelona              Spain   Wed, 20 Mar 2013 20:00:00

# To some extent…
~ rdio shows --artist="Mumford and his sons"
Sorry, I’ve never heard of Mumford and his sons
```


What say you?