[octavia] HTTP/2 support

Dear colleagues, - since haproxy supports HTTP/2 starting 1.9 (released on Dec 2018) for both frontends and backends - due to wide adoption of HTTP/2 (34% of all sites are now support HTTP/2 according to W3techs) - support for HTTP/2 is in all browsers and web-servers whether Octavia team has plans to add support for HTTP/2 as well? Thank you. -- Volodymyr Litovka "Vision without Execution is Hallucination." -- Thomas Edison