fix: Sort breadcrumbs before sending them to Sentry

[kamilogorek]

Ref: https://forum.sentry.io/t/bad-sorting-of-manual-breadcrumbs/3630/2

[HazAT]

LGTM 👍
Still, want to have @mitsuhiko blessing since we just talked about this in the morning and he meant it's not a good idea 🙈

[mitsuhiko]

We should not reorder breadcrumbs but figure out why they are incorrectly sorted in the first place.

[kamilogorek]

@mitsuhiko it's because you can pass the timestamp as one of the attributes to createBreadcrumb - https://github.com/getsentry/raven-js/blob/master/src/raven.js#L635-L640

Would you rather just override user's data by swapping the order of a merge?

var crumb = objectMerge(obj, {
  timestamp: now() / 1000
});