Feature: HttpClient should be pluggable to allow burp requests to be proxied by burp

[thomashartm]

The HTTP client is ready to be to be maintained as a separate module. By pulling it out it would be possible to reuse the core-framework and the scans lib as part of a security scanner extension such as burp.

Any request would then be routed through the scanners http engine and could be routed to a dedicated external-scanner-reporter to register security findings.