Modification for Ubuntu 13.10 and minor fixes in Neutron NEC plugin

Modifications for Ubuntu 13.10:
* Add .conf suffix to apache2 config files. In Ubuntu 13.10,
  files in sites-available should have ".conf" suffix.
  Otherwise it is not recognized by a2ensite.
* libglib2.0-dev is added to lib/files/apt/trema. Trema is
  an OpenFlow controler framework used by Neutron NEC plugin
  Ubuntu package dependency seems to be changed.

Minor cleanups are also done in OVS configuration:
* Set datapath_id before connecting to the OpenFlow controller
  to ensure datapath_id changes after connected.
  Previously datapath_id is changed after connecting to the controller.
* Drop "0x" prefix from datapath_id passed to OVS.
  OVS ignores datapath_id with 0x prefix.
* Fix a bug that SKIP_OVS_BRIDGE_SETUP skips all confiugration of
  the plugin agent. It should skip only OVS setup.

Change-Id: Ifac3def8decda577b5740c82fe8d24e8520c7777
Merge "Modification for Ubuntu 13.10 and minor fixes in Neutron NEC plugin"
Merge branch 'master' of github.com:openstack-dev/devstack