Use the content of the DOCKER variable in an array
Use the content of the DOCKER variable in an array

The environment variable DOCKER may contains more that one word, as in
DOCKER="sudo docker".

This is why the docker variable was not double quoted; but it does not
prevent from the globbing and word splitting.

This commits uses the content of that variable as a bash array to fixes
the shellcheck warning SC2086.

Note: The comments to ignore that shellcheck warning in the functions
docker_{build|rmi}() cannot be removed because the variables
DOSH_DOCKER_{BUILD|RMI}_EXTRA_OPTS are declared after the definition of
those functions.

[1]: https://github.com/koalaman/shellcheck/wiki/SC2086

gazoo74/dosh