Whitespace cleanup: convert tabs to spaces.
Refactor cancel script so that the bulk of it is in a function.

This is in prep for it supporting bulk cancellation, which will
iteratively (and recursively) call this new function.
Add support for bulk cancellation.

If jobs have dependents they can be cancelled as long as
the dependent jids have been passed in the bulk batch as well.
Make functions local, not global.
Merge pull request #13 from seomoz/bulk_cancellation

Bulk cancellation