Enhanced/add get redis config cmdlet

Now you can obtain redis config as Dictionary,

```PowerShell
Get-RedisConfig -Key save
```

this will return 

```
Key  Value                  
---  -----                  
save 900 1 300 10 60 10000
```

also you can set multiple config key as string[] like

```PowerShell
Get-RedisConfig -Key save, dir
```