RFC: tests/acceptance/bisect-acceptance.pl: automagic git bisect script.

.-| Request for Comments |-.
- automagically git bisect against the supplied CFEngine acceptance test
- hunt down the commit that either introduced a regression or fixed a bug
- respects bzr's notion of yes|no -vs- git's notion of good|bad; less
  confusing when hunting down the change that _fixed_ a bug.
- __required:__ invoke from ./tests/acceptance/ (atm).
- see https://github.com/cfengine/core/commit/804f23858286aa6101261688c3cc87ad1c0e89f5

@tzz (or any other perl wizards out there)- could use your perl expertise and black magic to take this from flaming pile to respectable. Gets the job done atm but limited and more-so embedded shell than real perl :-S

An example invocation:
```
./bisect-acceptance.pl --fixup --good=HEAD --bad=ff4dcdc ./01_vars/01_basic/009.cf
```