Requests with multiple query parameters of same name doesn't work

[nick-fedesna]

Issue: GET https://mock.vokal.io/v1/foo?bar=wing&bar=ding
Result: Missing File: GET|-v1-foo?bar=ding

When collecting the query parameters, we are using TreeMap<String, String> which therefore only allows for one of any key. We need to be using TreeMap<String, TreeSet>