moment-timezone prefers to declare itself as an amd style module

[CharlesWall]

Moment-timezone first checks to see if define is a "function" then checks to see if it is being declared in a module by checking for exports. This is not ideal. In situations (like mine) where your code ends up in a place where window.define is set and you are requiring moment-timezone as a node style dependency, the require returns an empty object and causes subsequent errors.

[CharlesWall]

I added a PR that fixes this issue. PR#573

There are four failing tests, but I get the same failures on master and develop.

[gilmoreorless]

I see from #573 that this was released in 0.5.18.