(SERVER-43) support basic auth in ruby HTTP client

This fixes the ArgumentError triggered by the http report processor.

**Testing**:  I've verified these changes manually.  Based on https://tickets.puppetlabs.com/browse/SERVER-43, it seems like there is an acceptance test which uncovered this bug - I'm hoping to hear back about specifics of the test, including coverage for basic auth.

It might make sense to hold off on merging this until we get the test situation sorted out, but I thought it would be at least putting this up for review.