Now sets the Content-MD5 header when an MD5 hash is provided via the setMd5Hash() method.

Still keeps track of a jets3t-specific MD5 hash metadata item "md5-hash" in case S3 ever changes the  digest used to generate ETags.
Now sets the Content-MD5 header when an MD5 hash is provided via the setMd5Hash() method.

Still keeps track of a jets3t-specific MD5 hash metadata item "md5-hash" in case S3 ever changes the  digest used to generate ETags.

dougm/jets3t,dougm/jets3t,dougm/jets3t,hyperic/jets3t,hyperic/jets3t,hyperic/jets3t