Build: add UMD support

[niksy]

This PR implements UMD support as discussed in #98 regarding "Support CJS internally".

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[coveralls]

Coverage remained the same at 88.288% when pulling ae9a49c on niksy:umd-support into 93c37d1 on jquery:master.

[dmethvin]

Awesome, thanks!

[dmethvin]

We may want to add return jQuery in outro.js so that it will return the modified jQuery when used with CJS. It's going to actually modify its incoming jQuery arg, but it seems like using the return value might be more natural. What do you think?

[niksy]

@dmethvin yeah, that makes sense! Do you think these change should be applied to 1x-stable branch, and not only to jQuery v3?

[coveralls]

Coverage remained the same at 88.288% when pulling a744cec on niksy:umd-support into 93c37d1 on jquery:master.

[dmethvin]

Yes, I can cherry pick it into that branch as well and do new releases for both.

[niksy]

OK, should I squash those 2 commits before merge?

[dmethvin]

I can squash them when I land it.

[mgol]

Why is jquery a dependency and not a peerDependency? This seems wrong as Migrate should be always patching an existing jQuery copy and not provide its own.

[dmethvin]

I remember thinking about this at the time, the issue with peerDependencies is that npm3 requires you to install them manually and I didn't wan't to do that. Maybe there is another way out? Perhaps just devDependency, since the Migrate code itself dynamically checks that there is a jQuery core loaded.

[mgol]

I remember thinking about this at the time, the issue with peerDependencies is that npm3 requires you to install them manually and I didn't wan't to do that.

There's no way around that. The purpose of peerDependencies is to depend on a package that needs to have one instance and you can't create your own. The correct way to go is to put it both in devDependencies and peerDependencies (the version range in peerDependencies should be more forgiving) and remove from dependencies.