Change report_interval from 4 to 30, agent_down_time from 9 to 75

Defaults values changed in neutron upstream to improve performances at
large scale.
Patch in Neutron: http://git.io/U1oCmA

Change-Id: Ie79668858eaa34de3872733af06b27e926593973
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
Change dhcp_lease_duration to Havana default of 86400

In Havana - the default lease time was upped to 86400 - 1 day - this should be changed back to the correct default in the puppet module as well.
http://docs.openstack.org/havana/config-reference/content/section_networking-options-reference.html

Change-Id: Ifd75f024186a9100f8aeb78415b4b5c8482913e2
Merge "Change report_interval from 4 to 30, agent_down_time from 9 to 75"