XMLHttpRequest broken after Axios migration

[jozsi]

Which SDK version are you using?

v21.0.3 (latest)

What's the issue?

#260

Steps/Sample code to reproduce the issue

Use in a browser environment.

Observed Results:

Http.request crashes.

Expected Results:

Http.request is the isomorphic function that routes either to Http.xmlHttpRequest (browser) or Http.requestPromise (axios, on backend). The following commit has replaced the request library with axios, adapted the code partly, hence creating a discrepancy: a2d64d9