Check for running docker daemon

[shanejbrown]

What does this PR do?

Adds a check to see if the docker daemon is running. If the daemon is not running it will print the exception with a message to check that the docker daemon is running and try again.

What issues does this PR fix or reference?

Without this check when you run buildrunner without the docker daemon running you get a vague error message.

Previous Behavior

Without this check when you run buildrunner without the docker daemon running you get the following vague error message:

docker.errors.DockerException: Error while fetching server API version: ('Connection aborted.', FileNotFoundError(2, 'No such file or directory'))

New Behavior

Now when you run buildrunner without the docker daemon running you get the following message:

buildrunner.docker.BuildRunnerContainerError: Error connecting to Docker daemon. Please ensure the Docker daemon is running and try again.

Merge requirements satisfied?

• I have updated the documentation or no documentation changes are required.
• I have added tests to cover my changes.
• I have updated the base version in setup.py (if appropriate).