Add placeholder for an Error which will be used in v2.0.0
Extract logic for updating progress into a 'update_progress' method
Add a method to check to see whether the bar has been started
Rather than specifying @elapsed_time explicitly, use the with_timers helper

That way if we add more timers or whatever, we don't have to change this in multiple places
Move the 'finished' logic into the progressable
Always thought it was weird that the 'finished?' check was in the update method
When checking 'finished?' make sure we check all progressables

This should probably be moved into some sort of helper. Maybe:

progressables.all?(&:finished?)
When finishing the bar, we also should stop the timers
Use the helper to divide the seconds.  Don't know why I didn't do this before
Add a warning that any changes to progress while the bar is stopped, will eventually be an exception
Changes to the total should also be considered a change in progress and should therefore not be allowed for a stopped bar
Remove the CannotUpdateStoppedBarError
Changed my mind. Rather than checking if the bar is stopped/started just blow up when the attempt is made to increment/decrement the bar to an invalid value
Merge branch 'bug/fix-incrementing-decrementing-bar-to-invalid-value' - #55

* bug/fix-progress-change-while-bar-is-stopped:
  Changed my mind. Rather than checking if the bar is stopped/started just blow up when the attempt is made to increment/decrement the bar to an invalid value
  Remove the CannotUpdateStoppedBarError
  Changes to the total should also be considered a change in progress and should therefore not be allowed for a stopped bar
  Add a warning that any changes to progress while the bar is stopped, will eventually be an exception
  Use the helper to divide the seconds.  Don't know why I didn't do this before
  When finishing the bar, we also should stop the timers
  When checking 'finished?' make sure we check all progressables
  Always thought it was weird that the 'finished?' check was in the update method
  Move the 'finished' logic into the progressable
  Rather than specifying @elapsed_time explicitly, use the with_timers helper
  Add a method to check to see whether the bar has been started
  Extract logic for updating progress into a 'update_progress' method
  Add placeholder for an Error which will be used in v2.0.0