Move boilerplate creation and completion of progress meters into method

[charlespierce]

As mentioned in the discussion here: #505 (comment), we have a lot of boilerplate around creating a progress_spinner or progress_bar, performing some action, and then tearing down the spinner / bar.

It would be nice to abstract that into a method that accepts aFnOnce for the task and handles the creation of the progress element, calling the task, and finally cleaning up the progress meter.