Make GettingStarted role's redis instance persist

GettingStarted depends on there being viable tasks in redis to work properly.
Having its data wiped whenever the machine is halted is very inconvenient. This
patch passes the 'persist' parameter to the redis class, which tells Puppet to
configure redis to sync its contents to disk every minute.

Change-Id: Ic5454bede98c5c248740e006d60be91be359bba0