Feature Request: Multiple Sort

Right now this is possible:

```elixir
iex(1)> Bind.QueryBuilder.build_sort_query(%{"sort" => "-name"})
[desc: :name]
```

But this is not:

```elixir
iex(1)> Bind.QueryBuilder.build_sort_query(%{"sort" => ["-name", "age"]})
[desc: :name, asc: :age]
```

Would it be possible to support multiple sort/order_by ?