Update docker's domain (docker.io -> docker.com)
Update docker's domain (docker.io -> docker.com)

`get.docker.io` is now redirected to `get.docker.com`.
As the curl does not follow redirections by default, now the command `curl -s https://get.docker.io/ubuntu/ | sudo sh` does nothing.

In addition, the current install script for ubuntu does `apt-get update` and `apt-get install lxc-docker`. Therefore, these commands are not needed.

https://get.docker.com/ubuntu/

scrapinghub/docker-redmine,scrapinghub/docker-redmine