2.4.0 -- Add :quiet option for watch task & bugfixes

- The :quiet option is now available for the watch task. It suppresses
  ANSI colors and the rolling stopwatch, printing only the elapsed time
  and possibly stacktraces if there are any exceptions thrown by the build.

- Prevent redundant :exclude clauses from being added to dependency
  coordinates in the boot environment's :dependencies key.

- Fix improper dependency calculations.