Docker daemon not started in concourse task (README example broken)

[Tom Fenech]

These two lines were removed from the example in the README:

source /docker-lib.sh
start_docker

But without them, any calls to docker functions cause the following error:

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

Since the entrypoint.sh script isn't used when a concourse task is run, these lines need to be in the task script.

[Dmitry Matrosov]

Good catch, thanks.

[Tom Fenech]

Also, since the docker-lib.sh script now has bash dependencies (e.g. declare), I think that the example should use bash, not sh.

[Tom Fenech]

Opened #16