Corrected multiple homebrew errors

Corrected the following errors with previous pull request
commit. All pointed by 'adamv':

  * Fixed `brew audit` suggestions
  * Added a tarball instead of specific commits
  * No parentheses in calls, 'ala ruby'
  * Removed test
New formula: lsusb - updated to v0.2

Main branch was updated with better style and practices,
script runs faster. Also improved the man page. All this thanks to
@paulp's suggestions.
Allow using brew tap instead requiring users to clone a fork

Move lsusb.rb formula to /.
Remove homebrew code.
Create a readme for installing the formula
Merge pull request #1 from nilbus/tap

Use homebrew tap instead of forking homebrew