Strip "launcher" strings from end of Cask names

There is a small inconsistency present naming practice: [readytalk.rb](https://github.com/caskroom/homebrew-cask/blob/163e52aa853c623345bf2398b3e0ea5bce0dff4e/Casks/readytalk.rb), [googleappenginelauncher.rb](https://github.com/caskroom/homebrew-cask/blob/163e52aa853c623345bf2398b3e0ea5bce0dff4e/Casks/googleappenginelauncher.rb) does not.

At 50/50 we don't have a prevailing practice, which is unusual.  This PR resolves in favor of removing "launcher" strings on the theory that they are generic and thus not helpful in search.