Alternative to OpenSSL for md5

[chuckatkins]

Currently you're using the libcrypto from OpenSSL for MD5 hashing of files when computing checksums. Since the only use of OpenSSL is for MD5, it's a pretty heavyweight dependency for just that. Would you be open to a PR that brought in a different MD5 implementation in order to reduce the dependency footprint?

[bnicolae]

Chuck, sure in fact we don't even mind switching from MD5 to a different checksum as long as it works reasonably well to detect corruption of data.

[bnicolae]

@chuckatkins: since we did not receive a pull request in a long time, I am assuming this is not an issue any longer. Feel free to reopen it if needed.