Convert Faking/Failing mechanism to new Configuration value

Converted Bamboo faking mechanism away from parsing out the GET param… …
…s into using a new Configuration value: addFakeRequest and addFailRequest.

Lots of changes to the tests to use the new format.
I was thinking that, then realised that you might want to overwrite previous fixtures. Unit tests specifically, where either something isn't cleaned up properly, or you want to override channels fixture which is set by default. Last one wins is fairly predictable so thought it'd be OK. Also it's hard to remove single fixture definitions once specified as it's keyed on the "substring" part so you've no idea what to remove, so it would be all or nothing if you couldn't override. Sound sensible?