Implement Jinja templates for haproxy config

Added templates dir
Added haproxy v1.4 template
Added template tests
Added jinja_cfg for new haproxy jinja templating

Partially-implements: blueprint lbaas-api-and-objmodel-improvement
Partially-implements: blueprint lbaas-refactor-haproxy-namespace-driver-to-new-driver-interface

Change-Id: Iad3a7be0146e1148b29edee56233aa3196c982dc
Co-authored-by: Brandon Logan <brandon.logan@rackspace.com>
Co-authored-by: Phillip Toohill <phillip.toohill@rackspace.com>
Co-authored-by: Dustin Lundquist <dustin@null-ptr.net>
Co-authored-by: Doug Wiegley <dougw@a10networks.com>