support style and explode for array query parameters

[jhannes]

E.g.

• style=form explode=true (default): a: ['1', '2', 'c'] => a=1&a=2&a=3
• style=form explode=false (or form=simple): a: ['1', '2', 'c'] => a=1,2,3
• style=space: a: ['1', '2', 'c'] => a=1%202%203
• style=spaceDelimited: a: ['1', '2', 'c'] => a=1|2|3