gave the cancel buttons a more meaningful label.
added new facility for mock vboxmanage command.

The mock feature is not complete yet, but it works!
indicate what vboxmanage command is being mocked.
corrected typo.
added condition to removal of tmpfile.
updated hardcoded constants for VB 4.3.

- storage controller chipset selection is now based on the controller
  type.
- additional choices for vb-list.
storagectl VB4.3 update.
isolated all vboxmanage commands.

This will aid with unit testing the vboxmanage side of the interface.
improved runcommand, and corrected errors.

- destructive command confirmation should be clearer now.
- changes tested manually.
Merge branch 'refactor'
Fixed rtcuseutc kludge, following fix in VB.