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: Phillip Toohill <phillip.toohill@rackspace.com>
Co-authored-by: Dustin Lundquist <dustin@null-ptr.net>
Agentless haproxy driver methods used by managers

Implemented driver methods that create network namespace and haproxy process.
Added tests.

Change-Id: Ia2abaedf9ef46110ce5b2d4e033c0f79ae68e089
Implemented lbaas managers

Change-Id: I08557ccf2936f8029ea60d07c285bb692d4c0b54