Stop vendoring ace.js and panzoom

[Godsmith]

I think we should stop vendoring these files and instead retrieve them from a CDN.

It doesn't make sense that we are retrieving some things, like bootstrap, from a CDN but other things we vendor. Also, it gives the impression that we have made changes to the code, but we have not.

This will also make grepping in the repo return less hits.

Not sure about the ace.js themes. If they are not in a CDN or similar they can remain, but then we have to add license information to the files.