Replace git submodules with npm packages.

[cburschka]

Currently, the libraries we're using are imported in one of two ways:

• buzz, jquery-contextmenu, filesaver, js-cookie, moment, strophe are all git submodules.
• jquery-replacetext and strophe-cadence are npm packages.

Most of the former are available as packages.

• https://www.npmjs.com/package/buzz
• https://www.npmjs.com/package/jquery-contextmenu (though I'm not sure of the versions, we might need to do #442 and upgrade to 2.0)
• Filesaver is tricky. The regular name is squatted by something else, and there are at least four candidates for an alternative, one looking shiftier than the next. All of them (like the original module) claim to be polyfills, but for an API that doesn't actually exist in any documentation. More research needed.
  • https://www.npmjs.com/package/moment

And, just published this moment:

• https://www.npmjs.com/package/xbbcode

[cburschka]

(The basic reason for this is that it is much less of a pain in the ass to update npm packages - instead of having to explicitly switch to a different commit and push the change to the repository, you can just update the checked-out code with npm update.)

[cburschka]

As a stopgap, we might be able to upgrade by using the workaround described here: https://github.com/swisnl/jQuery-contextMenu/issues/333