Merge branch 'master' into custom-extensions

.circleci/config.yml

openssl-sys/src/lib.rs

openssl-sys/src/libressl/mod.rs

openssl-sys/src/ossl10x.rs

openssl-sys/src/ossl110.rs

openssl/src/derive.rs

openssl/src/ecdsa.rs

openssl/src/hash.rs

openssl/src/lib.rs

openssl/src/pkey.rs

openssl/src/rsa.rs

openssl/src/sign.rs

openssl/src/ssl/mod.rs

openssl/src/symm.rs

openssl/src/x509/mod.rs

openssl/src/x509/tests.rs