Fix command-line-tools-lion cask

```
$ brew cask checklinks
Error: /usr/local/Library/Taps/caskroom-versions/Casks/command-line-tools-lion.rb:1: syntax error, unexpected '<', expecting tCOLON2 or '[' or '.'
class CommandLineToolsLion.rb < Cask
                               ^
/usr/local/Library/Taps/caskroom-versions/Casks/command-line-tools-lion.rb:7: syntax error, unexpected kEND, expecting $end
```