Added initial nginx services

Added initial nginx services

- Proxy allows ingress traffic to be sent to another element in
service mesh
- Mirroring is also in the default configuration
- Default configuration is to proxy to a clover-server and mirror
to snort-ids
- A location_path (URI in HTTP requests) can be reconfigured to
restrict proxing; default to '/'
- A proxy_path can be reconfigured to specify an alternate destination
- A mirror path can be reconfigured to specify where traffic
will be spanned
- The default server_port (listen port) for the proxy is 9180 but can be
reconfigured
- The default server_name is http-proxy but can be reconfigured
- Reconfiguration is done over GRPC with jinja2 template for nginx
- Currently snort ids sends alerts to proxy with stub code in GRPC

- Refactored the code to have a nginx base with subservices
- Proxy, Load Balancer (lb), and Server can share code - mainly GRPC
server
- Nginx subservices have separate docker builds

- Improved build scripts for CI
- Render yaml manifests dynamically
- Improve nginx_client for runtime modifications (but not really
useful yet)

Change-Id: Icbff6890021bcc8a8da4690c9261205d6e1ca43a
Signed-off-by: Eddie Arrage <eddie.arrage@huawei.com>