Make cache_ports configurable with default value of False.

[jkitchin]

This addresses issue #878 and #955. Suggested by @kevin-bates.

[jkitchin]

I guess I should have added a label. I don't know what this would be considered, I guess an enhancement?

[kevin-bates]

I don't know what this would be considered, I guess an enhancement?

Given the previous discussion a while ago, I view this change as something that should have been part of the original change and have applied the bug label.

[kevin-bates]

LGTM - thank you @jkitchin

[jkitchin]

Does anything else need to happen to this?

[kevin-bates]

We usually give folks a day or two to review. However, the build issue is also unwarranted but I believe it is probably unrelated.

@blink1073 - is the coverage issue due to some external version update or something like that? (Sorry, I haven't been "close" to the repos lately.)

[blink1073]

The coverage thing is a weird artifact from switching away from codecov where it seems like coverage isn't honoring relative_files = true in some cases. I've seen this on nbconvert as well.

[blink1073]

I'll cut a new release early next week.

[kevin-bates]

Thank you Steve!