Support deserializing duplicate query params

[iand675]

Query parameters are allowed to be repeated in URLs, e.g. status=PaidTrial&status=Paid. As far as I can tell, ember-parachute doesn't seem to offer a means of accessing these duplicate query parameters. I know it would be a pseudo-breaking change, but it would be great if duplicate query parameters would cause an array to be passed into deserialize rather than just passing in one of the params and ignoring the other.