Unpin rxjs if possible

[IanVS]

Hi, I see that you've pinned to rxjs version 5.2.0 instead of following semver with something like ^5.2.0. I am also using rxjs in my add-in, but at a different (more recent) version. Because of this, I now have two versions of the same package being bundled. Is it possible to use a more generous range for rxjs in this package?

Thanks!

[WrathOfZombies]

@IanVS Sure, we can upgrade the rxjs version to the latest minor version. We pinned it for consistency :)
If you'd like please send a PR with the change.

[IanVS]

Sure I can send in a PR. I'd suggest using yarn.lock and/or package.lock to maintain consistency, which will still allow consumers to use and lock to their own versions.

[WrathOfZombies]

We do check in a yarn.lock file, so feel free to update that as a part of your PR.

[IanVS]

Closed by #33