Change to handling of arrays in params

I have an application where I was posting things to a rails app using RestClient. I was running into problems where params that looked like:

```ruby
RestClient.post(url, { :foo => [ { :bar => "abc" }, { :bar => "123" } ] })
```

were getting turned into this the params:

```
?foo[bar]=abc&foo[bar]=123
```

which rails took to be:

```ruby
{ :foo => { :bar => "123" } }
```
which was incorrect. The http params should have been:

```
?foo[][bar]=abc&foo[][bar]=123
```
which rails turns into the correct hash and arrays as were passed in as params in RestClient.post