Fix #1824 add tabindex

- #1904 minor fix on image link

Docker Improvmement and small fix

- Resolve #1893
- Add syslogd to output sshd log on stdout (via `docker logs`)
- Enforce directory rights on `/data/git`, `/data/gogs` & `/data/ssh`
- Add `SOCAT_LINK` environment variable to prevent the creation of scout links when they are not needed (see #1815)

This reverts commit 94b2816446.

move minimum key sizes to config