Resolve deprecation warning from NTP module

Some time back the folks at Puppet Labs deprecated the autoupdate
parameter to the NTP module.  However puppet-coi still invokes
it, which causes a deprecation warning to be emitted:

Notice: Scope(Class[Ntp]): autoupdate parameter has been deprecated
  and replaced with package_ensure.  Set this to latest for the
  same behavior as autoupdate => true.

This patch eliminates the deprecation warning by removing the
deprecated parameter from our instantiation of the class.  A
corresponding change to puppet_openstack_builder will be submitted
to map the package_ensure parameter to a variable used to manage
a similar setting in other OpenStack classes.

Partial-Bug: #1281896