Add a cask-file for WebStorm
user
```ruby
class Webstorm < Cask
  url 'http://download.jetbrains.com/webstorm/WebStorm-6.0.2a.dmg'
  homepage 'http://www.jetbrains.com/webstorm/'
  version '6.0.2a'
  sha1 '4b6a1e0ccc3307c56acddc722e84476939d0129c'
  link 'WebStorm.app'
end
```
assistant