Add a version of deprecated_call which is a context manager

[pytestbot]

Originally reported by: Alex Gaynor (BitBucket: alex_gaynor, GitHub: alex_gaynor)

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This would be more convienent for deprecating things like "accessing an attribute"

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• Bitbucket: https://bitbucket.org/pytest-dev/pytest/issue/653

[RonnyPfannschmidt]

this can be done in the same manners as it was done with raises