Attempting to fix #724: Use provided target host credentials also when downloading via proxy.

[kaeufl]

trafficstars

Summary This PR tries to fix issue #724 by adding both the proxy credentials (if present) and the target host credentials (if present) to the CredentialsProvider passed to the http client when downloading node, yarn or npm.

Tests and Documentation Unfortunately, it seems there were no integration tests for neither the proxy nor the authentication feature so far. I could maybe try to provide one or two tests. It would, however, involve some new dependencies, since we'd need to start a simple proxy and/or http mock server of some sort prior to integration tests. Should you have any ideas/recommendations please let me know.

[t40mas]

Hello @eirslett, we have run into the same issue. Is there a way to merge #725? Unfortunately we can´t provide a fork in our artifactory.

Kind regards

Thomas

[eirslett]

Ok, let's go for it!