Fallback to docker image when local `arangod` cannot be found

[arangodb-helper]

Fallback to docker image when local `arangod` cannot be found

[ewoutp]

Given that arangod does not play well with file system mapping on mac/windows (map into docker containers), a direct mapping from local process to docker container is not really possible.

Alternatives:

• Start a docker container instead on a newly created docker volume
• Suggest to start a docker container instead (show how)
• Suggest to install arangod locally
• Both of the 2 suggestions.

[ewoutp]

@neunhoef please comment

[neunhoef]

I do not like too much automagic. So I am not in favour of silently starting a docker container with a new volume. I like the suggestion idea, though. How about printing "Blablabla not found, please install ArangoDB locally or do blablabla docker."