Fix 2.0 URLs for HTTP, allow_mult change, YZ tests

While none of the upper layers support it yet (no concept of bucket-types), the URL generation stuff will now handle the 2.0 response. Because `/buckets` and `/types` are fixed names and not configurable, it doesn't make sense to read what they point to, just whether they exist or not.

A number of tests assume `allow_mult = false` is the default. Changed this for 2.0 to assume `true` or test and change.

The yokozuna tests would often break between test runs, resulting in the result sets not having the correct cardinality. I've moved the setup machinery around so that the suite setup in `setUpModule` and `tearDownModule` only set the bucket up once, and cleanup any lingering objects in the index after each test run.