Merge branch 'release-v0.7.0' into release

.travis.yml

README.md

openssl-sys-extras/Cargo.toml

openssl-sys-extras/build.rs

openssl-sys-extras/src/lib.rs

openssl-sys-extras/src/openssl_shim.c

openssl-sys-extras/src/ssl_options.rs

openssl-sys/Cargo.toml

openssl-sys/build.rs

openssl-sys/src/lib.rs

openssl/Cargo.toml

openssl/src/bio/mod.rs

openssl/src/crypto/hmac.rs

openssl/src/crypto/pkey.rs

openssl/src/crypto/symm.rs

openssl/src/lib.rs

openssl/src/ssl/error.rs

openssl/src/ssl/mod.rs

openssl/src/ssl/tests/mod.rs

openssl/src/ssl/tests/select.rs