Add workaround for a crash occurring when running the Specs target on Mountain Lion [#68120746]
Spies forward -isEqual and -hash to the original object
Updates rake file to build against iOS 7.1

Runs iOS specs against 7.0, so 7.0 simulator is required
Stub and_do with a block taking the same arguments as the method
Invoke the stub's implementation block directly instead of using imp_implementationWithBlock

- First adjusts the invocation to remove the _cmd parameter entirely
- Also rename to and_do_block for now because of a greater chance of colliding with the existing and_do