default_url_options support in tests [8836]

We recently discovered that default_url_options are not honored in
functional and integration tests, and I dug up this patch by gcnovus
that fixes it. I've done a tad bit of cleanup, verified it against
edge, and am now soliciting for verifiers:

  http://dev.rubyonrails.org/ticket/8836

Thanks!

FYI, this wasn't actually helping integration tests (since within an
integration test you can generate urls independent of a controller). I
just uploaded a new patch that adds the ability to define
default_url_options either within your IntegrationTest or on an
individual session, and all rewriting that happens independent of a
controller will then honor those options.

Can I get some verification love?

P.S. Not naming any names, but since 7724 I'm getting an error in
FragmentCacheStoreSettingTest#test_mem_cache_fragment_cache_store...