Restructured docker building

I have restructured the docker build process entirely, the binary gets
built outside of the docker build command, now we are managing all
dependencies with real Alpine packages and I have dropped features like
socat or the cron daemon.

Signed-off-by: Thomas Boerger <tboerger@suse.de>

docker/etc/s6/gitea/finish

@@ -0,0 +1,2 @@
+#!/bin/bash
+exit 0

docker/etc/s6/gitea/run

@@ -0,0 +1,6 @@
+#!/bin/bash
+[[ -f ./setup ]] && source ./setup
+
+pushd /app/gitea > /dev/null
+    exec gosu git /app/gitea/gitea web
+popd

docker/etc/s6/gitea/setup

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+if [ ! -d /data/git/.ssh ]; then
+    mkdir -p /data/git/.ssh
+    chmod 700 /data/git/.ssh
+fi
+
+if [ ! -f /data/git/.ssh/environment ]; then
+    echo "GITEA_CUSTOM=/data/gitea" >| /data/git/.ssh/environment
+    chmod 600 /data/git/.ssh/environment
+fi
+
+if [ ! -f /data/gitea/conf/app.ini ]; then
+    mkdir -p /data/gitea/conf
+    cp /etc/templates/app.ini /data/gitea/conf/app.ini
+fi
+
+chown -R git:git /data/gitea /app/gitea /data/git
+chmod 0755 /data/gitea /app/gitea /data/git