Add a tool to reproduce HTTP KeepAlive races in OpenStack gate jobs.
Add a tool to reproduce HTTP KeepAlive races in OpenStack gate jobs.

Based on https://github.com/mikem23/keepalive-race

Change-Id: I11f66bf39c6cc2609ee0dbff97ac7b104767ac2b

JordanP/openstack-snippets,JordanP/openstack-snippets