Updated installing/installed application/extension messages.
Updated installing/installed application/extension messages.

- Running the 'a' or 'x' options will only show install
  activity for missing applications now. Otherwise, nothing
  will display.
- When installing new or missing software, there are messages
  for "installing" and "installed".
- Use the 'c' option to check the status of system software.

stevenqzhang/osx,masterots/osx_setup,empty23/osx,empty23/osx,BecomingCoder/osx