Configure OVS mechanism agent configs in its config file

Configurations for the OVS agent should go in its config file:
/etc/neutron/plugins/openvswitch/ovs_neutron_plugin.ini

Therefore, we should not remove the agent config file and
replace it with a symlink to plugin.ini or ml2_conf.ini.

Those config files are meant to be used by the core plugin itself
in neutron-server, not the agents themselves.

- Remove symlink creation from ovs_neutron_plugin.ini to plugin.ini
- Use neutron_plugin_ovs to configure OVS mechanism agent configs

Change-Id: I53d9b923784587e8a2a934f004a3b054c716daaa
Signed-off-by: Gael Chamoulaud <gchamoul@redhat.com>
Add manage_service feature

puppet-swift lacks of disabling service managing. This patch adds
$manage_service and $enabled parameter to all relevant classes.

Closes-bug: #1359823
Change-Id: I3d632e3a26e9394d03d94089ae704904bf77aa51