Update dependencies for OpenSSL 1.1.0 compatibility

Update dependencies for OpenSSL 1.1.0 compatibility

The primary targets here are openssl and openssl-sys crates 0.9,
bringing support for OpenSSL 1.1.0.  This requires updating the curl
and git2 related dependencies as well.

A small change is required in cargo itself for the new Hasher API.
Results from the hasher are simply unwrapped for now, matching the
Windows behavior that already panics on error.