#112 Get rid of Vue dependency in the code.

[cristijora]

Improve output bundle size by removing Vue dep and using moment.min.js
Reduced bundle size from 402kb to 176kb.

I think it's better to check if vue-multi-select is registered globally rather than checking if it's present in the window. Most of the time you register vue components with Vue.component... globally and don't necessarily put them in the window.

[icebob]

Nice PR. I did't know the this.$root stuff :)

[lionel-bijaoui]

I'm going to repeat myself from #114

I don't agree with the changes for moment.js.
By using the already minified version of moment, we reduce the chance of the minifier of vfg to do it's best job. It has to minify normal code with minified code, and I don't claim to know how it work, but I think that's not the best.
Also, we loose the sourcemap of moment.js.

I guess it I'm really nitpicking, but since the code will be minified at some point, why not wait for that moment (no pun intended). Or maybe minifying already minified code make it even more minified, and if it is the case, I'm sorry for my ignorance.

And I might add, the use of this.$root is super neat. Really well done ! 👍