[Etherpad] Migrate landing page here, autobuild

pica-etherpad/Dockerfile

pica-etherpad/README.md

pica-etherpad/landing-page/build/build.sh

pica-etherpad/landing-page/gulpfile.js

pica-etherpad/landing-page/index.full.html

pica-etherpad/landing-page/index.html

pica-etherpad/landing-page/scss/_call-to-action.scss

pica-etherpad/landing-page/scss/_footer.scss

pica-etherpad/landing-page/scss/_global.scss

pica-etherpad/landing-page/scss/_icons.scss

pica-etherpad/landing-page/scss/_masthead.scss

pica-etherpad/landing-page/scss/_mixins.scss

pica-etherpad/landing-page/scss/_showcase.scss

pica-etherpad/landing-page/scss/_testimonials.scss

pica-etherpad/landing-page/scss/_variables.scss

pica-etherpad/landing-page/scss/landing-page.scss

pica-etherpad/landing-page/static/css/landing-page.css

pica-etherpad/landing-page/static/css/landing-page.min.css

pica-etherpad/landing-page/static/img/Copyleft.svg

pica-etherpad/landing-page/static/img/bg-masthead.jpg