Merge pull request #101 from hannesm/fixes

CI: use docker image from ocaml/opam

silence warnings

adapt to new irmin and git

Merge pull request #100 from Armael/master

Html template: add a viewport meta to improve the rendering on mobile

Merge pull request #98 from hannesm/tls-0.11

README: adjust versions of tooling required

tls.mirage is now tls-mirage

Merge pull request #95 from samoht/irmin2

config: require irmin-mirage-git (and irmin >= 2.0.0)

config: generic_stack uses the socket stack by default now, no need for a conditional here

add _tags for checkseum and digestif implementation selection

use ocurrent opam debian image with ocaml 4.08.0, a more up-to-date node&npm

Minor cleanup