Remove _ExtensionKeyring. Any potential future keyrings depending on extension modules must implement their own full KeyringBackend subclass. Ideally, any extension keyring will be unnecessary, as it will be backed by a ctypes implementation not requiring a separate C implementation.

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extra : rebase_source : 58ef62d2e6cd16e047dd63839b5e0479903ea7f1
Four spaces per indent

--HG--
extra : rebase_source : 81bf74f8e1c15299b7af123a6c45773a20b4757b
Add implementation of ClassProperty

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extra : rebase_source : 56bee9aed78e5ccffda2d7a672e44048c4455cd3
Correct import of _win_crypto helper
fix #97 '__builtins not iterable on pypy'
Fix failing crypto test cases on Python 3