Rewrite HTTP handling engine

[gear54rus]

Do you want to request a feature or report a bug?
Feature

Your envieronment
0.0.9 Any

What is the current behavior?
We simply use HTML5 fetch to send HTTP requests and receive responses.

What is the expected behavior?
Use webRequest API instead.

The following functionality is needed:

• No automatic 401 prompt on auth failure: Code 401 makes browser display atuhentication prompt #15
• Restricted request/response headers: Add ability to set restricted headers #37
• Better error reporting if possible (TCP, DNS?): Better error reporting for 'fetch' requests #35
• APS Token refresh does not clear main response panel: Response panel is cleared after refreshing token #20

Videos/screenshots of the issue
N/A.