Inclusion request of fruit into Conan Center

Hi guys!

My name is Daniel and I am one of the https://conan.io developers. I recently reviewed your inclusion request to include the Conan Packages for your library `fruit` into the central repository Conan Center.

As you may know [we are not asking for any requirement](https://docs.conan.io/en/latest/uploading_packages/bintray/conan_center_guide.html) for library authors, only to keep in mind that you are responsible for maintaining the uploaded packages.

However, there are some things that might be interesting to do so I would like to give you some suggestions to improve its visibility and distribution:

- Include the license file of the library: This is important so every user has a copy of the license file whenever a `fruit` package is installed -> Add a ``exports = "COPYING"`` attribute to you conanfile.py
- Make sure to distribute the license in the packages with this line in the ``package()`` method: ``self.copy("COPYING", dst="licenses", ignore_case=True, keep_path=False)``.
- There are outdated from recipe packages uploaded. This means that some package were build with an outdated version of the recipe. See https://docs.conan.io/en/latest/faq/using.html#what-does-outdated-from-recipe-mean-exactly
- There are no packages for common platforms such as MacOS or clang compiler.
- Update the metadata in Bintray. This way your package will be easier to find: https://bintray.com/google/fruit/fruit:google

Most of this points are recommendations but please consider including the license in the packages as it is important for the distribution of the library itself.

If you have any question or need help with the changes do not hesitate to ask.

Thanks a lot!