Docker run and port  choosing

Hi !

First, thanks for the work you did on this project !
Second I know that @kim0 has already created a dockerfile for this tools (https://github.com/kim0/docker-yify-pop)... which work great !

However, I wanted to include this in your project as I made several changed to the way the ports can be choosen/allocated, in order to match the user's firewall pinning.

With your configuration file it was already possible to set the web interface port (4000). However, running within a docker container, one could not change the stream port (8889). and forwarding t this port was not working.

Therefore, I added de streamport config item set to 8889 by default.
Running yify-pop normally won't change anything.
However, if ran within a docker container it uses the docker-run.sh wrapper which changed the ports int he confiugration file, sets a var to force the stream port (bypasses the getport check) and then runs yify-pop

Hope you'll like it .
;)