Install lsof during Percona install

Percona's rsync SST requires lsof to be installed, it seems this does
not get installed on bare-bones debian images.

Sample error from /var/log/mysql/error.log:

    WSREP_SST: [ERROR] lsof not found in path: ....

Change-Id: I1b434f87d97cdf52b4458ab1f91b2df897530a0a