Adds HEAD request functionality with http_head

[thomascjohnson]

Added as a result of this issue: #20

This needs some cleanup due to the difference in response values for HEAD compared to GET and POST.

[thomascjohnson]

Just doing some testing on my end and my use case is to do up to hundreds of HEAD requests at a time. I'm seeing segmentation faults in some cases, and in general it would be good to have a progress bar on this. This is outside of the scope of this change, but I'm curious what your thoughts are on that.

[lmangani]

@thomascjohnson we'll familiarize with the change and run some tests to form suggestions/feedback
@ahuarte47 do you have any comments or preferences when it come to this feature?

[thomascjohnson]

To follow up on the seg faults, it's caused by URLs that can't connect and the headers being processed when they aren't available in the result. Just pushed a fix for that. I also fixed the issue with decomposition declarations.

[lmangani]

FYI The build failures do not appear to be the code's fault - I'll restart the jobs to confirm.

EDIT: tests passing

[thomascjohnson]

Thanks @lmangani! Looks like some of those URLs can be flaky? Any thoughts on adding tests with the extension httpserver?

[lmangani]

Thanks @lmangani! Looks like some of those URLs can be flaky? Any thoughts on adding tests with the extension httpserver?

yes indeed. We need a better public service for testing.