Added Bullet explanation to README.md
Added Bullet explanation to README.md

- README.md - Added explanation of how Bullet has been added to the
  automated testing suite.

Updates #985

EBWiki/EBWiki,BOWiki/BOW,EBWiki/EBWiki,EBWiki/EBWiki,BOWiki/BOW,EBWiki/EBWiki,BOWiki/BOW