Include basic editor(s): nano and vi(m) [tiny or minimal]

[corneliusroemer]

Context

Nextstrain shell is very useful to get a reliable no-worry environment. Sometimes I'd like to quickly edit a config file from within a session.

Description

Add small file editors to docker-base

Examples

I know nano is small, but as a vim user it would be great to also get a small vim version in, something like vim-tiny.

Downsides: image size goes up, but it should be at most a MB compared to ~700 we have already. I think that's ok.