feature request: add `exercism update` command

[glennj]

referencing #802

Instead of having to navigate to the exercise and click the "This exercise has been updated" banner then click the Update button, can we get a cli subcommand to do it?

exercism update --track=track --exercise=slug

And/or, a new option for the download command:

exercism download --track=track --exercise=slug --update

that would apply any updates prior to downloading.

[glennj]

Hmm, perhaps update is too similar to upgrade, or too similar for people familiar with apt. But I can't think of a better name at the moment.

[SleeplessByte]

--use-the-force-luke

update makes sense to me tho.

[asarkar]

+1 for an option to update the exercise without overwriting student solution. Until then, I'm using the following shell script (rename to .sh) for haskell track.

update.txt

[arlm]

Hmm, perhaps update is too similar to upgrade, or too similar for people familiar with apt. But I can't think of a better name at the moment.

I thought of using --sync because what I really would like to have my local exercises updated with whatever I change on the web editor.