Doubles

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- Native support for futures: `and_return_future` and `and_raise_future`

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- Allow with_args_validator to work with expectations

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- Added __name__ and __doc__ proxying to ProxyMethod objects.
- Expectations can return values and raise exceptions.
- Add with_args_validator, user_defined arg validators.
- Validate arguments of a subset builtin objects (dict, tuple, list, set).
- Update FAQ.

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- Add with_args short hand syntax
- Improve argument verification for mock.ANY and equals
- Fix pep issues that were added to flake8

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- Started tracking changes
- Add expect_constructor and allow_constructor
- Add patch and patch_class
- Add clear
- Clarify some error messages