Medium: mysql: Update mysql with more sensible defaults

The default values used by the mysql RA are outdated. This
patch updates the binary option to a more sensible defaults.

Don't try to use mysqld_safe by default as it performs its own
monitoring and restarting of mysqld which interferes with Pacemaker.
Also look in more places for the mysqld binary as for example
Red Hat-based distributions put the binary in /usr/libexec, not in
$PATH.