Change the rsync-ssl helper script

Change the rsync-ssl helper script

The new rsh-ssl-rsync helper script (replacing stunnel-rsync) supports
openssl in addition to stunnel.  The RSYNC_SSL_TYPE environment variable
can be set to specify which type of connection to use, and the first arg
to rsync-ssl can be --type=stunnel or --type=openssl to override the env
var or the default of "stunnel".  The helper script now looks for
stunnel4 or stunnel on the PATH at runtime instead of having configure
look for it at compile time.