Treat volumes_from, net containers, and links add dependencies for
service ordering.  Added depends_on to allow abitrary dependency
specification.

Signed-off-by: Gil Clark <gilclark1@gmail.com>

Updated unit tests.

Signed-off-by: Gil Clark <gilclark1@gmail.com>

Fixed bug with --no-deps on services with net container dependencies.

Signed-off-by: Gil Clark <gilclark1@gmail.com>

Remove sublime files.

Signed-off-by: Gil Clark <gilclark1@gmail.com>

flake8 based cleanup.

Signed-off-by: Gil Clark <gilclark1@gmail.com>

Fixed net container image.

Signed-off-by: Gil Clark <gilclark1@gmail.com> (+1 squashed commit)
Squashed commits:
[41be548] Refactored dependency management.

Signed-off-by: Gil Clark <gilclark1@gmail.com>
Incorporated changes suggested by @dnephin.

Signed-off-by: Gil Clark <gilclark1@gmail.com> (+1 squashed commit)