Add global error handler and renderer

[pkarw]

https://medium.com/the-vue-point/vue-2-5-released-14bd65bf030b

[kacperknapik]

worth noting: vuejs/vue#6953 (comment)

[kacperknapik]

According to the above comment, we have 2 kinds of errors - for simplicity, let's say, we have DOM Event errors, and 'everything else'.
At the moment, DOM Event errors, exceptions, etc, are not handled at all, they are silent and we don't know about them. 'Everything else' tho, throws [Vue warn] ... to the console. (as far as I know)
Thanks to this new errorCaptured hook, we can do something more with those errors (not DOM Event ones), but the question is, what do we want to do with them exactly.

I was thinking about the shop having 'dev mode', so we could place those errors to some kind of a HTML container, and show it to the devs. In 'prod mode' tho, errors will not be shown, instead, they could be shown in console only.

[pkarw]

OK, i think for now we could make use of: https://stackoverflow.com/questions/31472439/catch-all-unhandled-javascript-promise-rejections

and

https://developer.mozilla.org/en-US/docs/Web/API/GlobalEventHandlers/onerror

BUT it's need to be tested while offline because I'm affraid that elasticsearch-js is raising lot of errors when there is no ElasticSearch enabled which in our case is not an issue (we do have cachced data localy)

To display error page with the details dumped to dev console in that case.

I move it to 0.4 as it's not key for now