Fix: Regression on last commit for cluster destroy

[rafaeldtinoco]

commit c64ad9f created a regression when trying to fix the
cleanup part of "cluster destroy". The find syntax was tested
in a shell environment and os.system couldn't understand.
All files being searched are only contained in /var/lib/
pacemaker so this commit fixes that.

[rafaeldtinoco]

Sorry for the mistake. Now its good and tested:

$ sudo find /var/lib/pacemaker/
/var/lib/pacemaker/
/var/lib/pacemaker/cib
/var/lib/pacemaker/cib/cib.xml.sig
/var/lib/pacemaker/cib/cib.last
/var/lib/pacemaker/cib/cib.xml
/var/lib/pacemaker/cores
/var/lib/pacemaker/blackbox
/var/lib/pacemaker/pengine
/var/lib/pacemaker/pengine/pe-warn.last
/var/lib/pacemaker/pengine/pe-input.last
$ sudo pcs cluster destroy
Shutting down pacemaker/corosync services...
Killing any remaining services...
Removing all cluster configuration files...
$ sudo find /var/lib/pacemaker/
/var/lib/pacemaker/
/var/lib/pacemaker/cib
/var/lib/pacemaker/cores
/var/lib/pacemaker/blackbox
/var/lib/pacemaker/pengine
/var/lib/pacemaker/pengine/pe-warn.last
/var/lib/pacemaker/pengine/pe-input.last

[tomjelinek]

The original patch was working for me hence I merged it. Thanks for spotting and fixing this.