Publish .aar in a standard artifact repository

[cco3]

Has the uribeacon library been published in a standard artifact repository (like jcenter)? If not, would you all be interested in doing that? It would be helpful when building with maven/gradle to point to that instead of having to throw the binary into the source tree.

[dinhvh]

I think that for now, the .aar are published here: https://github.com/google/uribeacon/releases
If jcenter is a good standard repo, that'd be great to publish it here too.

[cco3]

The purpose of this is so that we can reference it in our gradle files. For an example see:
https://github.com/cco3/physical-web/commit/b8b90ea2a04289ddd29430a76999de9c3dcbcf9a

Without publishing to something like jcenter, we are stuck putting the binaries in our source tree.