Feature request: support for restic password command

[jessebot]

Thanks for maintaining this!

I wanted to request support for a password command. From restic --help:

--password-command command   shell command to obtain the repository password from (default: $RESTIC_PASSWORD_COMMAND)

Either that, or perhaps taking the password directly via the restic class with restic.password. In my case, I have the password in memory temporarily, but don't want to save it to a file.

[mtlynch]

Thanks for the suggestion!

This isn't something I use, so I wouldn't take on implementation, but I'd accept it if someone else wants to implement it.

[jessebot]

Sure, I can try and work on this in a week or two. If anyone gets the time ahead of me in the coming week or so, please feel free to cut me in line and submit a PR :)