netdev-dpdk: add dpdk rings to netdev-dpdk

Shared memory ring patch

This patch enables the client dpdk rings within the netdev-dpdk.  It adds
a new dpdk device called dpdkr (other naming suggestions?).  This allows
for the use of shared memory to communicate with other dpdk applications,
on the host or within a virtual machine.  Instructions for use are in
INSTALL.DPDK.

This has been tested on Intel multi-core platforms and with the client
application within the host.

Signed-off-by: Gerald Rogers <gerald.rogers@intel.com>
Signed-off-by: Maryam Tahhan <maryam.tahhan@intel.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>