added support for nested arrays as query parameters for bash examples

[eschricker]

Fixed: When using nested arrays as query parameters, the bash examples throw an exception.

Example: filter[category][]=2&filter[category][ ]=6 broke the existing code.

Solution: Check if the parameter is an array and handle it accordingly.

[shalvah]

Can you add a test? You can follow the examples in #603

[eschricker]

I restructured the code to support multiple nested arrays, as in the code for js, python and php.

In addition, I have extended the referenced test.