Make AndroidCertInstaller work with older versions of OpenSSL

The flag name to get the x.509 subject hash value changed in OpenSSL version 1.0.0. Some versions of OS X ship with older versions of OpenSSL, fix AndroidCertInstaller so it uses the correct flag.

BUG=431686
Merge pull request #33 from jeremymos/cert_installer

Make AndroidCertInstaller work with older versions of OpenSSL