support specifying volumes to mount with a more flexible syntax

[misterdjules]

Currently, node-triton supports specifying volumes that a container mounts using a syntax similar to docker run's -v command line option:

$ triton create -n some-container-name -v some-volume:/mountpoint:ro

This syntax has several issues, including not being able to specifying a volume name or a mount point that contains a colon character (':').

docker itself moved to a more flexible and robust syntax with the --mount command line option documented at https://docs.docker.com/engine/admin/volumes/volumes/#choose-the--v-or-mount-flag.

We should implement a similar command line option. The -v command line option would still be supported to preserve backward compatibility.