travis: build debian packages and documentation

The resulting packages are pushed to Debian repositories hosted on
bintray.com.

This is the first step to move away from our custom buildbot setup (see
https://i3wm.org/docs/buildbot.html for details on that) towards
infrastructure which is more standard (travis) and in the open.

travis/deploy-github-pages.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -e
+set -x
+
+GITVERSION=$(git describe --tags)
+
+mkdir build.i3wm.org
+cp -r deb/CLANG build.i3wm.org/clang-analyze
+cp -r deb/COPY-DOCS build.i3wm.org/docs
+cd build.i3wm.org
+echo build.i3wm.org > CNAME
+git init
+
+git config user.name "Travis CI"
+git config user.email "i3bot@i3wm.org"
+git add .
+git commit -m "Publish docs/static analysis for github.com/i3/i3 v${GITVERSION}"
+
+# Hide stdout/stderr because it might contain sensitive info.
+set +x
+echo "git push"
+git push --force --quiet "https://${GH_TOKEN}@github.com/i3/build.i3wm.org.git" master:gh-pages >/dev/null 2>&1