This will allow the use of different crypto libraries in the future.
Modified-by: Andrew Ayer <agwa@andrewayer.name>
* Don't include openssl/err.h from git-crypt.cpp
* Fix whitespace and other style to conform to project conventions
* Remove unnecessary operators from Aes_ctr_encryptor
* Rename crypto_init to init_crypto, for consistency with init_std_streams()
