Log Message:
Update rake to 0.8.1.

Changes:
* Added task parameters (e.g. "rake build[version7]")
* Made task parameters passable to prerequisites.
* The 'task' command will now accept task argument names.
* Comments are limited to 80 columns or so (suggested by Jamis Buck).
* Added -D to display full comments (suggested by Jamis Buck).
* The rake program will set the status value used in any explicit
  exit(n) calls. (patch provided by Stephen Touset)
* Fixed error in functional tests that were not including session (and
  silently skipping the functionl tests).
* Removed --usage and make -h the same as -H.
* Make a prettier inspect for tasks.
* Removed ftools and parsedate requires for compatibility with Ruby 1.9.