Adding EiffelStudio as a homebrew package

Hi,

I've just added a package for Homebrew to install EiffelStudio.

Let me know if there is anything more to do.

Thanks,
Manu
Can this test be modified to do something more substantial than e.g. `--version` or `--help`? See `cmake.rb` for an example of an application formula with a good test and `tinyxml2.rb` for an example of a library formula with a good test. Thanks!