refactor artifacts
- abstracts out common logic, much code removed
- fixes one bug/inconsistency: some artifacts failed to
  "return false" when the target exists in "preflight_checks".
- one trivial functional change: artifact type and quotation marks
  added in all user feedback (quotes needed b/c of pathnames
  containing spaces)
Adding cask for Activity Audit

Adding a cask for application time tracking software DssW Activity
Audit.
add feedback when downloading a URI source

otherwise the user sees the curl progress bar w/o explanation
Merge pull request #2300 from rolandwalker/refactor_artifacts

refactor artifacts
Merge pull request #2304 from rolandwalker/uri_feedback

add feedback when downloading a URI source
Merge pull request #2302 from DssW/activity-audit

Adding cask for Activity Audit