WIP: Add GitHub release support for Linux and OSX

[okapies]

Ref. https://docs.travis-ci.com/user/deployment/releases/

TODO:

• Add an archive which contains all dependent shared libraries instead of libmenoh itself
• Add menoh_onnx_viewer to the package

[msakai]

Sorry, I overlooked the review request...

[msakai]

It generally looks okay to me.

Some notes:

• It might be better to package make install/striped version of libraries/executables, but I'm not sure as I'm not very familiar with cmake.
• For packaging macOS binary, it might be better to specify osx_image: or MACOSX_DEPLOYMENT_TARGET to specify the lower bounds of supported macOS version.

[okapies]

Thanks for the comment. I'm inspecting the cmake configuration for static linking. I'll going further after these tasks are finished.

[msakai]

Note that now there are multiple jobs for same platform due to #81 and #83.
It is necessary not to upload same file from multiple jobs.