docker: exposure on non-reserverd ports
- BETTER Changes port number exposed by docker to non-reserved ones to avoid conflicts with local installations. Webport is now 28080, Redis 26379 and MySQL is 23306, which is a simple +20000 shift from the standard ports.
- Replaces PNG diagram in docs with SVG version.
Signed-off-by: Marco Neumann <marco@crepererum.net>