sysvinit files

Adds sysvinit files as mentioned in #2.

This is just the simple setup I use which I provide here without much configuration ...

... but the essentials for configuration are already there: You should expand the config file `/etc/sysconfig/redmine` (which is already sourced by the script) to the variables you mention in your README and also add the bind mounts and maybe the container name and container exposed ports. Then you should expand the init.d script with bash syntax like:

    ${SMTP_PORT:+-e "SMTP_PORT=$SMTP_PORT"}

... to turn existing / non-empty variables into `docker run` command line arguments. I guess, you could even move the defaults you have in `resources/redmine` to this config script and separate concerns:

- `etc/sysconfig/redmine` is just configuration
- `resources/redmine` is just for setting up the container internals