Bump Savon requirement to 2.x
Mock and stub using the builtin Savon methods

Saying goodbye to savon_spec and Mocha
Change leftover Mocha-mocks/stubs to RSpec ditto
The WDSL is always fetched from disk
Make the test suite pass again
No logging in tests for new

Primarily because I didn't see an easy way to set the logger without having to
instantiate a client
Use Savon 2 style client API
Properly stub the response when we also need headers returned
Assume successful requests when nothing else is specified
Use the cookie abstraction in Savon 2

Sure beats messing with cookie headers ourselves