tests/ovs_client: Remove broken debug code

There is some debug "logging" code included in the 'ovs_client'
application. This code appears to be broken as it spams stdout with
duplicated "log" messages. Remove this code.
This patch also renames ovs_client to ring_client.

In addition, add the 'test-dpdkr' executable to the 'tests/.gitignore'
file.

Signed-off-by: Stephen Finucane <stephen.finucane@intel.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>