Add Dockerfile for redfishtool

[jallirs]

This commit adds a dockerfile for redfishtool.

[jautor]

Discussion 9/19: Can you provide some background on this? There are environment-specific paths in the scripts (and it assumes bash is available), so we're not sure if this can be made to work on anyone's environment.

But any documentation that could show how one could customize these to work in their environment would be helpful, too.