Drop OpenSSL 0.9.8 (#2978)

* Drop OpenSSL 0.9.8

* Drop this test, it's not relevant any longer

* unused import

* Remove CRYPTOGRAPHY_ALLOW_OPENSSL_098=1 from our tox

* removed unused code for Cryptography_HAS_PKEY_CTX

* return unused code for _AESCTRCipherContext

* syntax :-(

* remove some unused tests and skips

* remove unused code for Cryptography_HAS_PBKDF2_HMAC

* Revert "return unused code for _AESCTRCipherContext"

This reverts commit 7d149729205aa4c9735eb322414b167a75b302df.

* Remove unused RSA code

* Remove unused test code for conditional bindings

* Remove unused dsa code

* unused import

* Remove unused x509 extension code

* Remove unused EC code

* Attempt to remove unused DER key loading code

* document this

* grammar

* Added back this paragraph

* Update docs
13 files changed