Simple flag to have machine-readable snip get output.

[LarsFronius]

Use-case being that if I adopt snip as a team with a shared vault, I'd want to call snip from scripts and retrieve a secret in plaintext.

For now the best option I found to get plaintext output of a secret value is:

snip get foo -q -o /dev/stdout

A convention of lots of programs would be to accept - in place of stdout to shorten the command.

A different option could be to implement a flag like snip get foo -r (-r/--raw for raw output mode).