Fix transmission not resuming torrents on docker stop/start

[dougnukem]

Closes #23

• Ensure TRANSMISSION_HOME is on a persistent volume to store torrent resume info
  • https://trac.transmissionbt.com/wiki/ConfigFiles

[haugene]

Hey. Nice addition, I like it. Would you mind submitting your PR to the dev branch? I've made some changes to the image as well and then I could test it all together before merging.
I also addressed the persistent state issue. I separated transmission scripts copied into the container from the folder keeping transmission state. This allows for mounting a separate volume for the transmission state.

I propose to keep both options. Both provide transmission_home as a configurable path, and allow for a separate mounted volume for the state. Sometimes you might want a separate mounted volume, but for the most part /data/transmission-home is the easiest option. Maybe set transmission_home to the /etc-path as default? I don't know, I prefer that the default run option starts with a clean slate.

[dougnukem]

New PR opened #25