Currently, the fact that `os initialize` requires elevated permissions
forced us to require calling commands that reuse it, such as `device
init` and `quickstart` with administrator permissions as well.
This ended up causing issues like saving images in the cache that belong
to root, or initializing git repositories that requires `sudo` to
commit.
The solution is to call `os initialize` as a child process preppending
`sudo` within `device init`.
Fixes: https://github.com/resin-io/resin-cli/issues/109
- Add helpers.confirm() to abstract the process of asking for
confirmation.
- Add helpers.selectDeviceType() to abstract the form needed to ask for
device types.
The functions on this module are reused by app actions.
