Fix Conventional Taps Name

Taps which come from homebrew do not have `homebrew-` in the title, but ones from other repositories typically do (eg `josegonzalez/homebrew-php`, `phinze/homebrew-cask`).  However those taps would be installed in directories called `josegonzalez-php` and `phinze-cask` respectively.

The correct conversion for those would be to remove the `homebrew-` part first, then convert the `/` to a `-`.