Switch to the new BzAPI compatibility endpoint

[edmorley]

Whilst there is a PR open to switch to the new REST API (#25), the legacy third party BzAPI endpoint is going away within the next week or two, so a shorter term fix is required.

To avoid disruption, please change references of form:
https://api-dev.bugzilla.mozilla.org/latest
...to new BzAPI endpoint:
https://bugzilla.mozilla.org/bzapi

Migration to the official Bugzilla REST API can continue after that, in PR#25.