Move forked "a2" dependency into mozilla-services org

[tublitzed]

Following best practices to not tie production code to our personal repos, let's move this dep out of a personal repo and into the mozilla-services org before we deploy this to prod.

[AzureMarker]

Let me know if you need any help from me.

[jrconlin]

https://github.com/mozilla-services/a2

[tublitzed]

@jrconlin can we also change the dependency in this repo to point to the newly created https://github.com/mozilla-services/a2? https://github.com/mozilla-services/autopush-rs/blob/master/autoendpoint/Cargo.toml#L15

[jrconlin]

We may want to consider either owing a specific fork of this library, or replacing it with a more actively supported library, since the original library seems to be abandoned.

[tublitzed]

Yup - worth looking at for sure. In the meantime, can we scope this ticket to simply replacing the link to a personal repo with something that we own? After that, we can look at replacing the lib separately.