various updates
  * .gitignore :
      - updated with several more files to ignore

  * BackoffCaller.php :
      - added BackoffCaller() - Basic implementation of Backoff with a sleep() delay and a callback

  * Backoff.php :
      - added BackoffCaller autoload

  * phpunix.xml :
      - added some default php.ini settings to set on run
      - added test/ directory to the list of excluded dirs
      - added verbose and strict attributes to phpunit node
      - updated to show untested files

  * readme.md :
      - misc formatting for better readability
      - removed unusable html code
      - updated readme to reflect the new BackoffCaller class