Proposal: "tmkms init" command

[tarcieri]

I'd like to propose a "tmkms init" subcommand (ala "gaiad init") which creates a KMS directory structure at the given path.

It seems there have been a few questions about this in the past regarding people who couldn't figure out the directory structure. It now includes a number of files/paths so I think this would be helpful.

It also means we could customize the generated configuration based on what cargo features are enabled.

Thoughts?

[liangping]

This subcommand is very helpful.