Conversion from vector to matrix through Matrix constructor

The following should be implemented:

```
Matrix([1;1])  # Now 2 by 1 matrix
```

since that is a very explicit and readable way of the conversion.

Context: The issue was raised under  JuliaLang/julia#9208 where a recommended solution was to convert a vector `[2.0]` to a matrix using `[2.0]''`. I think `Matrix([2.0])` is more readable and accessible to newbies than `[2.0]''`.
