Indexing matrix returns 2D row on Julia v0.5

```
a = rand(10,10)
a[1,:] # Returns row in Julia v0.4 and a vector on Julia v0.5
```

Currently, ArrayFire returns a 2D row just like in Julia v0.4, but unlike v0.5.

```
a = AFArray(rand(Float32, 10, 10))
a[1,:] # Returns a 2D row
```

Start by reproducing the AFArray indexing example from the issue and locate the implementation of row indexing. Compare its result with Julia v0.5's a[1,:] behavior; done means AFArray indexing returns a vector rather than a 2D row for this case.

Scritto dal modello di indicizzazione a partire dal testo della issue.